NO retrofit kit should be used...
Use the right Compressor for R134a and the right Freon and oil.
Anyhow, didn't the 92 models come with the R134a already???
It seems that you have a leak in your system. You need a new receiver drier with the right pressure switch then you need to draw a vacuum and see if you have a leak...
Or you could just put everything back in place and draw a vacuum to see if the system is holding the vacuum... Probably work with nitrogen also to see if the compressor works.
Anyway you look at it, get at new receiver drier when you put everything back together.
Is your Compressor R134a compliant?? Did you rear the koalamotorsport page?
'85 Euro 635csi Race Turbo, megasquirt, Group A
'92 525i Touring 5 speed, 3.46 diff, UUC 8.5lb flywheel, soon to be turbo.
'02 Subaru WRX Wagon with STI springs, bigger sway bars