I am overhauling A/C on '86 760T because the old compressor seized and R12 and oil remains are black. While I am at it, I will convert from R12 to R134. I have David Urban's intructions "Volvo AC Retrofit for 740/940" (thank you David and Brickboard). I have a new Seltec (OEM) compressor for R134, a Volvo conversion kit with a receiver, fittings, ester oil, yellow O-rings and so on, a Volvo supplementary kit with pipes and fittings, even a new pressure hose because the old one is a bit worn. I will have R12 and oil remains taken out at a shop, but I am not stateside and standards are lax. Question is:

What do I have the shop do, OR DO MYSELF, to flush and remove from condenser, evaporator and lines all debris, like metal particles from old compressor, and all trace of R12 and its oil that could contaminate the new compressor?

Thank you very much.