the A/C compresser mounts on the pass side of the engine. the PS pump mounts on the drivers side. so with or with out PS wont affect the AC install.
there are not many parts to the system.
I think it could be done in less than 7 hours.
But I imagine life would be easier if you ripped off all the AC parts from a wrecked toyota, along with the HVAC unit. if you choose to go AFTMKT with all the compnents it probly wont be so easily bolted on.
but remember, once you get it all installed it wont be charged with freon. and using parts from a say, 86 uses R-12. And to refill that stuff is very expensive compared to the new stuff R-134a.
So before diving into it, consider these options
can you find a truck that has already been retrofitted?
are you a pimp and can you actually get poontang if your trucks cold?
How much would it cost you to retrofit the R-12 system?
if not retrofitted, besides the compressor how much will it cost AFTMKT parts, compared to a retro fit kit?