I have an old petersons article on converting the long style older AC compressors found on 60's,70's,early 80's GM cars/trucks, which is what I plan to do. I got the pieces already. I'm putting an oiler on the intake and a de-oiler on the output, back to the same resevoir. This is what the writeup did.
The article does mention the newer shorter axiel type compressors found on mid-80's up GM cars/trucks, they said they are not good candidates for OBA, don't rememeber the reason. The older long style they said, however, worked just as good as any purchased OBA kit or york setup, the only problem being the oiling which you have to take care of yourself. They actually converted 2 trucks, to see how long the compressor would last without any oiling. In the many weeks they ran the thing without any oil at all, it never broke, it got hotter than the one they did with oiling, but as of the writing of the aritcle, it was still running w/o an oiler. But, I think I'd like mine lubed.