Adding factory AC to my non-AC 1970 truck

[demian5]

I scored a fairly complete working system (minus condensor, compressor brackets, hoses, and controls). But boxes, cables, evaporator, heater core, ducts, even a good AC glovebox.

I can get the parts missing locally unless someone has some they want to part with.

Bonus is my truck already has an AC dash and I can do all the work myself.

Any gurus that have done this have any advice? I figured ill pressurize the EVAP core and check for leaks and replace the heater core just to prevent needing to later, along with a new receiver drier.

How do I need to modify my firewall?

Are there upgrades to the POA valve or oriface tube that I should do to bring it up to modern technology?

I have R-134 at my disposal but freeze 12 I can get too (and have gauges for both).

Anything else?