Most performance rebuilds on 302 heads include installation of Chevy V8 intake and exhast valves. 1.94 intake and 1.5 or 1.6 exhausts. This is only a modest increase over stock - You will need hardened seats in the exhaust anyway, and the Chevy seats are readily available. Any additional cost for reaming guides or cutting new spring seats should be offset by the dirt-cheap cost of the valves. Check with your machinist and weigh the options.
