You probably have a hydraboost pump then. Check and see if your PS pump has three lines coming out of it. If it does, then it is indeed a hydraboost pump and you'll need to have a hydraboost master cylinder to make it all work.

If it has 2 lines coming out of the PS pump, then you're all good to go. Just route the two lines to the steering box on your OBS and it'll fit in like the old one.