Not that this helps your quest, but I read somewhere recently that the limiting factor on the LT5 was the longer term survival of the peripheral stuff, e.g., alternators, & AC compressor bearings, etc. 8k was (author unknown) more of a limitation on the stock LT5 itself. Case in point: What rpm was Pete's LT5 turning when he hit 129.xx mph in third gear with the 3.45 rear gear??
P.