OldIHC

I am thinking of swapping 264 out of an R162 with a diesel. Any one out there complete a swap successfully and what did you use?
Thanks.

A Cummins 5.9 12 valve will fit that truck like it was made for it. My friend has installed the Cummins 24 valve in "L" pickups. the fit is tight but nothing needs to be cut. The pickups need frame strengthening. I think the frame in a 160 should be strong enough' I bought an R150 frame for a Cummins powered "R" crewcab project. The 150 frame is more than strong enough.
A difficult to find Cummins 4bta should be slow but adequate power and fitting it in is no problem.
Buy a derelict Ram 2500 for the engine and transmission. This can be the most economical way.

I swapped a 6.9 IH Diesel V8 into an R120. The sound was fantastic. The fuel economy was more than twice as good as the SD220. The power, while much improved, was a little disappointing in the hills. I would not recommend using a 6.9 of 7.3.

Depends on what you want. If diesel is your only factor than one of the Cummins engine Nikki mentioned will fit the bill.
If you want more power but diesel isn't required, a Keystone turbo kit is another option. Plenty of upgrades can be made depending on your skill. If you add fuel injection, an intercooler can be used along with higher boost. More than enough "wow factor" and plenty of tinkering you can do to keep you busy for the foreseeable future.
Gasoline is cheaper than diesel and will likely remain so in the future. They operate over a broader speed range so work better with available ratios in the truck already. A diesel may require a ratio change or an aux trans to get the truck down the hiway.
Don't get me wrong, I am not anti diesel, I have a fleet of them, and have had them in everything from farm tractors and cars to heavy trucks. Unless you plan to run 10 hrs a day 5-7 day a week, I don't see the benefit of diesel. I don't own anything small with a diesel anymore. I will never own another "car" used for short trips to town or work with a diesel. Just not worth the hassle.
Some people just want a diesel for the "cool factor" and if that is where you are coming from, the Cummins is likely better than the other small/light duty diesels available.

I can't stand the smell of diesel from all my years working in the orchards with diesel tractors running all day,

I'd put a built gas engine in myself, but your truck build it your way,

Gasoline is always more expensive than Diesel here. Today the gasoline is 23 cents per liter higher than Diesel.

As a point of reference, I just checked Gas Buddy and regular gas is selling at a wide range here in Central Florida: $2.33 to $2.79/gal.
Diesel: $2.58 to $2.95/gal.
As Cornbinder89 said, unless you have a specific reason to need to have diesel power, gas is going to be more economical. And I understand the fuel pricing varies by region so it’s really your call.
If I was going to go for an unusual power plant, I’d investigate the turbo charged inline six cylinder. Might even consider the twin turbo variety. My F150 has the 3.5L Eco Boost v-six and I can tell you it has a lot of power (365hp) and torque (450lb/ft). I also fully understand that it’s all newer computer technology, but who’s to say you couldn’t apply some of this technology to an old rebuilt engine for that outer edge cool factor. Nikki built a computer controlled supercharged flathead engine. The parts and pieces are available if you don’t mind researching them. Still, your call.

Slight correction:
I do own two small diesels, one in a Kubota tractor and one I had in an APU I made back in the 90's. Nothing in an Automobile.
Kubota and Yanmar make good small diesels, but most are too small for Automotive use.

There is more energy in Diesel fuel. This can be 14% to 17% more energy.

One has more energy/lb the other more per unit volume IIRC