i have another thought on the person kneeling next to jack's engine: he's a tech with champion and that is a champion dyno. notice the champion logo on his shirt and the overly-large champion sticker on the dyno. in the days when this pic was taken, there were very few cars outside of indy that sported a turbocharger, let alone two of them on a big block chevy, and this cat just wanted to get a picture of him with it. in later years, jack lowered that plenum quite a bit and added an intercooler that, in its day was state-of-the-art, but would be sneered at today. this looks like a modified hilborn; i think what he used later was self-constructed.