Any Issues: Old Condenser - New System?
I agree with Doc - do yourself a favor and move on up to R410A. I know it's pricey, but if you can't do it right, then you should just consider waiting until you have the money to do things right.
You won't be able to reuse the coil with R410A when you have to upgrade that condenser. Yes, you can change the TXV back to 410A, but you will be very hard pressed to get all the old mineral oil out of that coil, and it doesn't take much at all to lock down that new 410A system. I've had the local Rheem/Ruud tech guys say that they won't warranty system if they find that the coil was not changed out when a new 410A condenser was installed. I can't verify that, but I sure wouldn't take the chance.