Daughter needs Gas mileage from 273 commando

Badger p275 is a 2 barrel piston. Advertised 8.8 to 1. The specs are on the NHRA site under 273. You have small chambers with the 64-65 heads. Sounds like a great build. The only thing I'd change is the cam, for your intended use. Not exactly a mileage build. I say it'll pull past 6K and get there quick. You better change that tranny fluid and filter. Best adjust the bands and pump up the pressure also. Best mileage will be at higher speed than 55, like Hemichuck says above. You will just need to find where that is. Pretty wicked car for a youngster. You will love it, and at the same time you may be afraid to turn it over to your daughter.