Carbking, I'd be interested in the details on your 68. I'm also working on a 68 gmc. My first mileage check was 15.25 but I found that the choke was not opening completely so I'm hoping to do better on the next tank. I have a 292 with 390 holly 4 bbl and HEI. All the internals of the engine are stock. I have an A833 OD transmission and 3.73 rear gears. It runs about 2000 rpms at 60 mph.
