Feedneck is a proprietary thread (7/8 27npt) close to NXT but isn't correct and won't hold well with the limited thread contact on the A-80. I have a die that I used for my A-80's to put CP's on them. Turned out fairly well.
HPR also has a proprietary connection, but if you get an adapter made any reg that puts out 100-200 psi reliably should work. Or you could run a female Stabilzer on the grip to the stock reg after gutting it to just act as an air through.
As for wiring diagram I'll see if I have a pic of the back cap/board on my pc. If not I'll get one of it later.
This is what I have on hand, from when I was bringing one back to life.
Battery harness is soldered to the board. First 2 connections on the terminal are to the trigger switch right most 2 are for the solenoid.
The MOST important mod you could do is cut a piece of plastic or cardboard to fit inside the main body between the bolt and chamber for the wiring so your wires don't get guillotined (like above).