I have the 7K3's on my 400/461 build and they are really good for the price. Mine were free with the 72 400 from the local scrap yard. Already had 7/16" studs with polylocks. I cleaned the bowl area, ported and did a gasket match and filled the exhaust crossovers with molten aluminum. They work and sound great. I have the forged Sealed power pistons at zero deck so my compression is about 9.5. I use 93 octane and have a 2802 cam to keep the detonation away. BTW, pulls like a freight train! I also drilled and tapped the end holes for headers and inserted a 3/8" stud. Took about 1/2 hour on the drill press and is why these heads are so cheap. They match the higher regarded 96's except for the header flange bolts needing to be tapped and a stud installed. With 4 tube headers and the exhaust crossovers filled it cleans up the muddy exhaust note that Pontiacs have versus Fords or Chevy's.