NO! It's a K so keep in this section,in this case "size doesn't matter"
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Unfortunately Irish Mike doesn't have the books for this model but,going with the truck's class it very likely has a Hydro-vac brake system.
I highly doubt anything off the donor truck's air brake system wheel brakes can be "swapped" to a K,but without knowing the spec's (F & R axles) of both trucks it's hard to be sure. I do have the MT-140 parts manual for '79-'83 S1600-1900's,which might be helpful(?).
Since the donor has AB's you have a compressor so the idea of an air pac is viable giving the "tractor" air over hydraulic brakes and eliminating the H-vac.This leads me to ask what size if the compressor,7-1/4,12,13 or 16 CFM? It's questionable if a 7-1/4 would be able to sustain enough air for trailers and maintain the reservoir tank(s). That's not a real problem since remote mount comp's have the same base size a larger one will fit the mount and probably only require new hosing.
The radiator is also questionable,how many rows does it have and how much pressure will it handle? The DT in an S-series should have a 15lb cap and a surge tank IIRC(?). I'd check fitment of the donors rad. (if possible) and see if it could be used along with the surge tank.
What about the air cleaner? The S-Series one is pretty big and mounted on the firewall,will it fit under the K's hood? I kinda think it won't espeaialyy with enough space for the surge tank. It reminds me of the R 190 up when they had a Cummins,the AC had to mounted on the right cowl/fender. If an external AC is needed I'd check an older Mack R or U model (yeah,yeah,so sue me!) and see if it can be adapted,they're very close to what the IH R's used and probably much easier to find.
Those are just what came to mind after reading this thread,I'm sure it's only the tip of the iceberg of things to check into.
I'd have to reiterate what Brian/Nikkinutshop and others tell people contemplating such an endeavor,make a detailed plan and list
before beginning.