Makes sense, I estimated the hp in that motor around 600-650, and obviously with 10 years on it I'd say it's ok. Omar, your point is taken, but that cost was just the cost of the conversion, not line boring, lifter index, sonick check, etc. At some point, at least IMO, it pays to start with a solid foundation. The way I see it, if you're building enough HP to warrant a 4 bolt conversion, the extra amount for the new block is probably not that much in the grand scheme of things... I realize of course, that that quote could be high and maybe there is somebody out there that will do it cheaper.