88 a/c - converting r12 to r134a?

[thaubol]

Ive got an 88 monte carlo that im pullin apart for my 68 gmc build. so far ive got the motor pulled, and i was thinking about using the air condition from the car in my truck but id really rather use r134a instead of the r12 that the system currently uses. does anyone know what is entailed in converting a r12 system to r134? i know its possible and have seen 'kits' but i figured id ask to get some background. thanks