up to 70, and there no better than a set of j u o head as all the runners are the same on all heads. If I were doing a restoration I would buy a set of j o or u with the 1.88 intake and have it machined for the 2.02 valves ,this is like buying a new head as there has only been 1 valve job done to them, I would buy a j head over the infamous ,lol, x head as their crap to begin with as your flow #s dictate, buy a set of eddies or victor if you want to go faster than 12s in the 1/4 mile. no offense meant but the x heads are way overrated and way misunderstood .