Hydroboost question has been addressed, but let me add - if you follow the rubber lines from the master cylinder, they connect to the power steering pump. These should be replaced when you have a chance, because if you blow one, what a total mess all over the engine compartment. IMO, it's worth keeping them, but you may have to do some fabbing to replace stuff. The challenge is that the brake hoses tee into the pressure and return lines, and I don't know if truck hydroboost lines will work on the GP. If you choose to rip it all out and replace it with a vacuum booster, make sure you get the rod through the firewall to the pedal and the booster brackets from the donor car. Then post the hydroboost on the Forum, and you might make back the money you spent on your conversion from someone who wants to run a wild cam.