I want to revive this ancient thread because I'm building a 1 series track car with S65 swap and wanted to remove AC for weight savings. I [think I] found the golden ticket to this... the S85 never swapped belt direction and the PS pumps are all over the place for fairly cheap, and bolt right on.
The mounting bracket from the S65 has to be swapped over since the mount is slightly different on the S85. The input connection is at a slightly different angle on the S85 pump but it doesn't appear to be an issue. If it leaks I'll just replace that pipe with a more flexible one with worm gear hose clamps.
Since I haven't fired it up my only though/concern now is the flow rate will be significantly different and the PS will feel too heavy or too light, but I doubt it. I'll try really hard to remember to report back when I get the car together.
UPDATE: Car is together and drives perfect with the S85 pump.
I had to try a couple different belts and you'll want a 31.5-32" belt. I found the KRC 4060320 that fits perfect.
S85 PS pump PN: 32412282951
Belt: KRC 4060320
https://www.krcpower.com/ecommerce/part-gdy-4060320.asp