Rebuilding a 292 L6 70´chevy truck

[ChevyMex]

This truck is a present from my father, He bought it brand new and since 3 years ago i am rebuilding it. My question is, i have found another truck in a salvage yard and i took out the factory air system and i am thinking to install it in my truck, but it seems that there were not too many 292´s or 250´s with A/C systems since i have had terrible time trying to find the brackets for the compressor, if anyone has an idea, place, website or a design that i can copy, so i can place the compressor, i will appreciate it.

Also, i found that this system has POA valve that the new systems dont, How i now if it works?, if i use a POA eliminator will all stuff i have bought like, lines, fits, conections, tubes, expansion valve, dryer work or do i need to send them back and buy new ones?

Since i am in Mexico and the law do not prohibit R12 i will keep it and not retrofit to R134, i have heard that R12 works better than R134

Please respond whit anything, i do not have too much knowledge about A/C systems