I had a 86 Sub., armored vehicle heavy. My wife got 8-10mpg hauling kids around for several years. They just don't do much better in my experience. And 200HP from a 454 was just depressing. As long as the shaft bores are ok the carb should be ok to rebuild. Edelbrock not original, hopefully it is their Qjet spread bore replacement and not a Edelbrock Performer. I've tried Performers (square bore) on 454's and they never have done as well as the Qjet with mpg.