Since you apparantly don't have a leak, an R/D might not be necessary unless it's just been ages since last replaced. I do now believe that you did indeed have a restriction.

If you can find a shop with a recovery/recycle machine set up for R12, you might be better off to pay them to recover, replace the TXV and recharge with your refrigerant. That way you keep your reserve in hand.

Since you're in Dallas McCains probably has an R12 machine and they are reliable and reasonable in their pricing. That said I haven't dealt with them in several years, but if Mark is still there then I expect that they are still golden. In fact if Mark is still there, call him and tell him what you've found. He is a very helpful and approachable guy and one of the few people around that I'm comfortable with when it comes to leaving my car with someone.

One of my machines is set up for R12, but it has a bad controller board. I'm not sure if I'll ever get it fixed.