Retrofitting a R12 A/C system?

Hey guys, so my cousin just bought a 1993 Honda Civic Coupe and like most older Hondas, the AC doesn t work and on top of that it also needs to be retrofitted since it uses the old R12 system. I have some experience working on cars but need a second opinion on this one. I would much rather do the work myself that way I learn in the process as opposed to just paying someone to do it and call it a day. Buying and installing the new fittings is not a problem, the refrigerant is what s got me confused. I know R134A is not compatible with R12 and can cause problems if the system is not evacuated properly. I can have the whole system evacuated for 20 bucks which will solve that problem. Oil is also not a problem opted to go with ester 100 and use the adequate volume for the car. My question is, is it more straight forward/ Convenient to just use R12A or just go with R134A? I m aware that these refrigerants also have a different mass and exact amounts have to be calculated. If I opt with R12A, would I need to even evacuate any remaining R12 from the system? Now of course I m assuming that there are no leaks in there and will have to do a test to see if it holds vacuum but if it doesn t that will just be another problem that I have to resolve. Any feedback is appreciated, thanks in advance.

Read more: Retrofitting a R12 A/C system?