Yep, I think I am going to buy a drum of 134a. I’m still running r-12 in most of my old stuff from a drum I bought many years ago.
Might have to see is any of the small junkyards will let me evacuate the systems in the junk cars. Supposed to do it before scrapping them anyway but I think most people just let it out into the air. I've got a filter to remove any leak sealant that might be in a system. That will muck up my recovery unit(s).