2005SSR6speed: I know that the pushrods on the LM4 engine are shorter than on the Z06 engine, due to the smaller cam base circle required on the Z06 cam to get the higher lift. Is there also a difference in the pushrod lengths between the LM4 and the LS2 engines? (I would assume there is, due to the much higher lift of the LS2 cam). If so, replacement pushrods would be one difference between the 03 / 04 and 05 / 06 kits.
What engine rpm range would the "blower cam" operate in? If above 6000, the stock LM4 valve springs need to be replaced for reliability long term. (I limited my LM4 to 6200 rpm until I got the Z06 valvetrain). The stock springs in the 05 /06 are of course fine to 6500.
But, if I were doing a CNC head package, I think I would consider the possibility that the buyer might NOT go with a supercharger, at least initially. In that case, the CNC heads and the cam, coupled with good exhaust changes, could make a real high rpm screamer, in which case lightweight but strong valve springs, pushrods, and retainers good to say 7000 rpm might be a great thing to include in the kit, OR add as an option. Then, depending on inertai loads in the crank, rods, and pistons, 6800 or 6900 rpm might be reliably attainable. The Gen III engine is VERY mechanically strong even in bone stock form.
Could be fun . . .
Jim G