If you're going to keep R12 in the system, then do it right and get a new condensor. They are NOT expensive, and if you look at napaonline.com, you might even find one there. Not sure about that, but it's possible. I'm sure that they're available on the aftermarket, or you can go to a dealer and get it there. It does cost you, but if you get one from a salvage yard, you do run the chance of the thing springing a leak after a short time (or maybe right away) and wasting that expensive R12.

I'd personally do the Volvo parts 134a conversion with the new, appropriate condenser, since you now have a reason, and then to hell with any part in the system. If it leaks later on, just keep recharging. And you won't have to worry about the 134 getting away if you change the compressor or something else blows a gasket somewhere. With the R12, you're out a LOT of money if you can't get someone's stash of R12.

Ford Certified or whatever, it isn't a problem.