In my humble opinion and from what I have read and gathered from builders, about 400hp at the flywheel. Between 5800-6000rpm you run into valve float on rollers unless you upgrade the springs. I would think 500+hp in a street 302 isn't going to last long. The folks at this web site are very helpful and they build both street and racing engines. http://www.tandlengines.com/
Ed
Ed