Jamie, I wouldn’t dismiss what James Bostick has told you, I’m going to side with him also on this topic. The GM rectangle port iron heads are great, there is a lot of potential in those heads, but you have to ask yourself, how much more power and speed are you really after?. Remember one important thing, bigger WILL NOT guarantee you more power, bigger port volume can hurt overall performance due to loss of velocity filling the cylinders, the only way to get the velocity back along with volume is to turn higher RPM, (piston speed), your pump is now in question, what’s your max RPM now? We all know how important cam selection is, Flusher spoke of loosing dynamic compression, this is another concern with big lift and long duration cams in an engine that won’t see the necessary RPM to justify these components. Usually in larger displacement engines we can have cams custom ground with a wider lobe separation to get the dynamic compression back, not requiring as high of RPM to fill the cylinders adequately. Sounds like you have money burning a hole in your pocket, just be wise in your choices, also going with a big solid roller cam may require more maintenance and upkeep, also quicker valve spring fatigue. Taking some of these expensive steps may not give you the results your looking for, and also put you in a category of giving up some reliability and fun. If your 496 is healthy it should be putting out close to 600hp, I just built a 489ci BBC with 781 oval port heads with the larger valves and mild port & bowl work and it dynoed just shy of 600hp, hell my 10.0:1 467ci with shit box slightly worked peanut port heads made 541hp on the dyno. It’s all about the complete combination within the useable rpm range along with everything working in harmony to produce good power.
