Does the RV2 compressor have its own oil sump? If not, note that R-134a is not miscible in the mineral oil used in R-12 systems... and modern compressors depend on the refrigerant to carry the oil and keep the compressor lubricated.

Compared to R-12 the low side temp/pressure curve is not identical, although it will work OK. An expansion valve calibrated for 134a is preferable.

I'd really recommend a better condenser, or at least a pusher fan in front of it, or you may be unhappy with the performance at idle. Central TX is a pretty hot place in the summer.

If you're not concerned with anyone else ever servicing your system, or the legality, and it's leak-tight, you could consider Envirosafe ES-12 (propane/butane mix). Cheap and effective.