[Gunner]

I think I've made the point I stepped in to make: that 1960s engine tech is good for about 1.1 HP per cube and no more, not while retaining anything like street driveability. Even drag engines of the day didn't have significantly higher power ratios. Speculation about what modern tech adds, and how that relates to old tech capabilities, is meaningless anecdotal bar chat.

I'll throw in one more datum: If anyone could get the most out of these engines for road racing purposes, it was Shelby working with Ford. He hit the wall in the power curve right about where I've stated it. When he wanted more power, he didn't screw around with tech that was as-yet undeveloped (extensive porting, valve changes, displacement increases, deep-breathing intakes of normal size, etc.) No, even Unca Shelby "cheated" and just grabbed a Paxton or two off the shelf.

If Shelby couldn't do it in the day, I'd venture to say it couldn't be done.