I have had no issues using the 2 cylinder York Compressors with R-134a. Just be sure to drain all of the oil out and use the Ester oil. There is a plug on both sides of the compressor body used to drain and refill the oil. When you fill it, lay the compressor on it's side and fill it with oil till you can stick a dipstic in and see 9/16" of oil on the stick. You can use a coat hanger, a 7" ty strap or anything that is straight and will fit through the hole. The Yorks are a good pump, but tend to vibrate and make a little noise. Thats why they had those huge Flywheels on the pulley, to smoothen out the vibrations. A Sanden is lighter and more efficient.
One of the problems in converting older R-12 systems to R-134 is the R-12 condensers are not as efficient as the ones designed for R-134a. So, on a really hot day the A/C wont cool and the high side head pressure becomes excessive which can cause seals to fail. If you have the CAA kit that shouldn't be a problem. If the York compressor you have was manufactured in the last 10 years it'll have the updated front seal.
On a side note, the Sanden I have in inventory, which is an official Sanden from CAA (I am a dealer) was made in Singapore and the Sanden Corporation is based in Japan.