Can I did a little deeper on your situation. When you say the whole system, You mean, evaporator, condensor and compressor. I would love to stick with r 12. ( I am getting certified so i can but it) 20.00$. Thanks for the pics.
The car came from up north, so apparently the AC was not used as much as we do here in Okla/Tex. Thus, the compressor was in excellent condition. When I removed everything from the firewall and all the hoses, I capped off the compressor.
I bought a new main hose, which included the hose going out to the condenser and over to the POA valve. After I had the tiny hole repaired in the bottom tube of the condenser, I flushed it out along with the remaining tubing. I installed a new dryer with a sight glass.
I removed the entire unit from the firewall (requires removing the right inner fender), boxed it and shipped it. Classic Auto Air completely disassembled everything, rebuilt the POA valve, rebuilt the expansion valve, refinished everything like factory, and adjusted the POA valve for R12.
Basically, all I had to do was assemble everything, with new O-rings, vacuum the system and charge it. I left the vacuum pump on for 18hrs, shut it off and left it for 6hrs. the gauge NEVER moved. Then I charged it. It's been working perfect and blowing 38-40deg air since 2012.
Our 70 conv was a factory 307/3sp on the column.
I would love to have a BB, BUT, to change to a BB would require rounding up EVERYTHING for the conversion. I had some rebuildable SB400 cores, which would literally be a drop-in bolt-in swap. So I built a very healthy SB400 with a complete cowl induction setup and replaced the 3sp with a built M22W, and rounded up a floor shift steering column to get rid of the original column shifter knob. I have ZERO regrets!