Its a lot easier to check now then once its together. Carbs will run a slant so don't worry if it doesn't come out just right. The driveline is more important. As long as both ends have approx. the same angle, they will cancel each other out and run smooth, doesn't matter if pinion is pointed up or down.

I removed 1/4" spacers from under my motor mounts trying to get clearance at the radiator and didn't notice any difference in ride or vibrations, so its not real critical to be right on the money. Maybe I should measure the angles now to see how far I moved it!
Joe