I've got a 235 powered 3/4 ton (1952) with 4.56 gears and I average between 13 and 14 mpg on the highway. Shockingly bad for a tiny little one-barrel carb, but I see everyone else gets around that too. As long as I don't commute in it, it's okay.
52 GMC 3/4 ton pickup 68 Big Block Vette 68 455 Firebird