Hi,
If you are planning on fitting a modern A/C compressor then don't go bang up to date, a current compressor effectively run constantly, they are then controlled by Pulse Width Modulated Signal from the engine control unit to govern how much ' pumping ' they do, so under acceleration they are almost turned off, on cruise etc they do just enough to keep the desired temperature constant, its all about emission's now a days.
As far as using old pipes then the valves will need changing or adapting as old gas R12 uses screw on filling pipes and 134a uses a snap on type.
ALWAYS fit a new unopened receiver / drier, the silicone gel inside become clogged with moisture out of the atmosphere in 24 hours, once in there it can not be removed and so is trash.Internal moisture is the enemy of a A/C system. It clogs component's, degrades oil and will combine with refrigerant to produce an acid to corrode your system from the inside out. I always pull a vacuum for at least 1/2 hour before charging, when you vacuum the system it lowers waters boiling point, so allowing it to be sucked out as steam from pipes etc.
Cheers John
LIVE LIFE A QUARTER OF A MILE AT A TIME!
1976 Speke FHC Beauty Now with an overdrive conversion
1979 3.5 FHC(STATUS PENDING!!)
1982 2.0 DHC NOW A 4.6, BUILT NOT BROUGHT !!!!