A/C retrofit '**740 non turbo wagon

[JAGCHiker]

Has anyone retrofitted the original freon system to the new coolant? I've heard that all fittings, o-rings need to be replaced in system due to molecular difference in coolants. The Volvo retro kit doesn't look like it has o-rings for entire system. My AC hasn't been used for over 8 years since freon got way too expensive; and living in local that doesn't need AC; so expect an empty system - easy disassembly; and lots of leaks.