I have a set of hydraulic roller lifters that came from the engine Im rebuilding for 400hp. Theyre the stock GM ones from a 1989 350 2 bolt main. Can I reuse these lifters? Am I correct to think that roller lifters have a significant gain in hp over flat tappet lifters? Either way, im going to go with hydraulic. If I could reuse them, I would, but I just thought id make sure.