Welcome aboard. If you can swing it you would definetley want at least 500hp. That would put you right about 63-64 maybe 65 in the right conditions. I have 635 or so @ 5lbs of boost and I'm running right @70 and saw 72 once

. But I'm still working on the setup and x-dimension! I have a buddy with with a NA/540CI and he makes just under 600 and he sees 67-68 on a regular basis. They are heavy boats for a single and need some power to get them moving, but once you do you will love the ride. There is plenty info on here if you do a search. Let us know how it goes.
Scott