Well Adam, if you're asking whether these (049 or 781) heads are good for what you want, the answer is yes....The 781's will be a little easier to find, but one is the same as the other, identical castings (for all practical purposes anyway) With bigger valves, (or even stock valves) and a little work, they will easily support a 5500 rpm engine, and if you go with the larger valves, will work nicely on your future 496. Those castings are considered my many to be one of GM's best 'as cast' production heads. John