[GMCNUT]

I may have a set of the one and only, true, real deal holyfield factory AC brackets GMC made for this engine I could send you to replicate from. Easy work overall as this spare set was already re-made using my original bracket set I lent a buddy so he could make them, and they turned out perfect. Using GM's already-engineered work to re-make the brackets you need allows you to use the A6 or the newer high efficiency A6 look-alike compressor on the left side of the V6, and it clears the power steering pump perfectly.
I will also make a post of my 1965 factory Air find I just brought home from Colorado and I will detail the bracket setup to see if this is a set you want to replicate. You'd still struggle with V6 pulleys maybe but there are enough of those around off 401, 378 and other "big truck" applications to dig up some pulleys or maybe someone will get clever and have some spun up from billet.

For anyone with questions about the GMC factory assembly-line installed AC that was first offered in 1965, buzz me anytime at 256 486 1988. I have learned a lot in my years and am the only person in the country who has really focused on GMC AC knowledge through owning 3 complete operating factory AC trucks and multiple loose systems.