Place a level on the intake manifold where the carb sits. The level should be zero, this will give you a about 3-4 degrees downward tilt of the tailshaft on the trans. If you look at the carb base on a Chevy intake, it is not level to the valve covers. If the carb is not level you will have floar problems. MAke sure the difference between the centerline of the diff and output on the trans is as close as possibe 3 degrees is ok, but 1/2 to 1 degree is better. If the difference is to great, you will get Ujoint binding and wear.
Besides watching the Dist clearance, watch your fan to radiator as well. If you plan to run headers, make sure that you clear the steering box.
