I don't know, but for the record i ran
[email protected] with a 3,000lb 66 nova on pump gas about 20 yrs. ago with a 406" motor with ported double hump heads. We could then buy 100 octane.
I will say that i tried Edlebrock, and all other manifolds. The only one that preformed good was a holly, i ran duel 660 center squirters and they perfomed great even at 110 degrees temp day time in Phx. I also ran the same setup on a 377" and it ran 10.50's in the same temp. In my views there has not been a tunnel ram that out of the box out performed the holly tunnel ram.
Today with cam advances and good heads i can now run that with a 750 holly on a single plane manifold.
Either way if you want to run a tunnel ram i would choose the holly.
Just my .02
Zip.