A/C Compressor and Conversion Kit


I'm looking to replace a leaking a/c compressor along with a conversion kit on my 86 635csi. I would like to convert from the old (and expensive) R-12 freon to the newer 134 freon. Can anyone recommend a specific manufacturer and seller offering these items?

PS: My car has the rear seat cooler box above the rear a/c vents-although I'm really only concerned with the functionality of the front dash a/c vents...

Thanks and Cheers :)