Cold air induction

Would cold air induction help performance? I know the perfect mounting spot for the box but would like to know before i spend money on it

Well, as they never realy had heated air intake, cold air will not make much differance.
Heated air intake allowed for better atomozation and prevented "carb ice" in humid conditions. That is why almost all cars have had some sort of heated air intake from the mid 60's. Even most fuel injection systems require it to prevent carb ice (throttle body ice).
These old engines had none of that, so you had to have hand thottle and manual choke just to keep them running.

Ah, then why does everyone put CAI on all these newer cars?

mostly its hipe. In theory, the colder the air, the more dense and the more fuel that can theoritcally be burned.... BUT the fuel must be fully mixed with the air to fully burn.
In a all out race engine,where driveablity isn't a factor, just all out power the cooler you can keep the intake the better.
In a street driven vehicle there is a reason that mfg ALL used heated air intakes. Being able to keep the engine running in high humidity without stalling every time you try and idle is worth the very slight density penilty, add to that the better atomization in a heated intake mix, the theoritical increase from cooler intake is all lost in poorer atomozation of the fuel.
Make all sort of claims, without the double blind test data to back it up and you can sell anything. Just look at the "turbo air cell" that is supposed to "spin" the incomeing air, losta of hype, but no double blind test data. Same with "fuel magnets". All have "testomonials" from users claiming all kinds of advantages, but none have tests data from repetable test where they take measurement before, then after install, the remove and retest for the orignal data, then re install and try and duplicate the 1st results.
The true test of anything is a test where neither the operator nor the people analizing the data know whether the unit is stock or has the "modifacation" done. There needs to be "stock" and modifide units and then the mods are switched to the other unit and the test done again. Only then can you be sure that the results are from the modifaction or from some other factor.
Don't forget, "all the newer cars" are port injected, where the fuel is mixed at the back side of the intake valve, which is a whole lot hotter then heated air intake. Your truck, the fuel is mixed relitively far away from that point and in a much cooler area.

Cold air induction does not cool the air per say. The advantage is that it draws induction air from outside the engine bay, so the air entering the intake is not heated by the engine. In reality it is not cold air, but relatively cooler air. Cooler air has a higher density, thus containing more oxygen per volume unit than warmer air. This increases performance. On a newer fuel injected engine, it does increase horsepower and fuel economy, but by fractional amounts. I have installed a cold air induction kit on some of my cars and does provided a bit of noticeable improvement, both seat of the pants and at the pump. The companies that sell the systems such as K&N, Airaid etc perform dyno tests to prove out their claims of increased HP and torque for their systems. Do your research before you jump head long. There is a lot of hype and there are a lot of different set ups and you want to get what is right for your application.

Personally I like the 60's style cold air induction, A nice big hood scoop! MM

BUT, modern fuel injection uses a air mass meter to measure the amount of air entering the intake BY WEIGHT (mass) where as a carb meters fuel by the VOLUME of air passing thru the venturi and has no way to tell the mass, so it meters the same regardless of density. No benefit , and likely so drawbacks would be seen in a carb'd situation.
If cold intakes air provided such great benefits, don't you thik the engineers at the auto comapnys would a figured that out? It is such a competitive field. Seat of the pants, and fuel records are easly skewed by hopeful feelings, the only true test is double blind, over many units, over a long time.
Theory says there should be some gain on a modern fuel injected vehicle, but not much and there may be an equal penelity that will nulifie any gains, in driveablity or low to mid throttle settings. Anything with a throttled intake is subject to iceing at part thottle at temps as high as the upper 50's to low 60's.
For there to be any beefit at all, a feedback fuel system would be required to adjust the mixture for density, the old carb system was never that precise and has no ability to adjust for density.

Another thing to consider: these old inline 6's have the carb and manifold hanging off to the side. These engines don't have the carb and manifold sitting on top of the engines, being assaulted by hot engine oil like V8's do [think SBC here]. If your exhaust manifold heat riser on the old 6 is doing its job correctly, exhaust manifold heat is only influencing the intake when the engine is cold; that bimetallic spring closes the plate as the engine warms up. On the other hand, unless you modify the V8 intake, you have some exhaust in the crossover the entire time the engine is running. So any benefits from cold air induction for these old inline 6's will be pretty much negligible. When the stock engine is functioning properly, you've already sitting at "as good as it gets" for a carbureted engine.

Thanks guys, thats why I ask questions first spend money later

Best bang for the buck would be a Keystone turbo kit. A fair bit of cash all at once, but will give a whole lot more then little things can. Still, when compared with all the cash for an engine swap, is still wise money spent.