motor plates

so i have the bbf and my 64 fairlane,with the KFM motor plates front and rear.its all new set up.what is the most important part of aligning the engine?with the rear end,pinion to the trans/driveshaft angle?or the carb pad being level?i have a lot of room up and down to move the engine if need be.the way its in the car now it has a approx 3 degree angle of the front frame to the motor plate.is that normal with the carb pad being level at ride height?this is a stock frame car with shock towers and leaf spring rear.

2 to 3 degrees is correct.

Each U-Joint needs to have from 1 to 3 degrees difference through it.

O.E.M. "fore & aft" engines are all over the place from 1 to 7 degrees and sometimes even angled a bit sideways 1 or so degrees or off center on the chassis up to almost 3 inches.

Use the best compromise which will make the entire vehicle run the best it can be.