10mpg out of a Holley 850? Yeah, maybe if all of the planets are aligned. I'd guess more like 4-6mpg.

*Edit: That thing has an M22 transmission, so at best, a 1.0 4th gear. I'd imagine, since it's high performance, that it has a decent rear gear, like a 3.23 or shorter. No gas mileage!

Also, I wonder how many JDM fanboys got excited when it said it was restored using, "NOS." That's New Old Stock guys, not nawzzz.