Sounds like you might be considering putting on a compressor that runs off the engine... One possible source would be Therold Industries. They make a commercial compressor kit that is belt driven off the engine. When I looked into them some years back they had one for the 1GEN Cummins.
They offer a 4CFM compressor @ 125 PSI. They call the compressor system "Ready Air"
You can reach them at:
Therold Industries
500 E. 7th St
Holtville, CA 92250
(619) 356-4515
------------------
Andy Raiha
96/2500/4x4/4. 10/5sp/CC