If you are using stock location engine/transmission mounts on a backhalfed, big tire car, driveshaft operating angles are usually wonky to some degree. Never run a positive operating angle on the rear u-joint to get the pinion parallel with the trans output shaft, which is typically about 3* down with OE mounts. If the engine is being put in on motor plates this can be corrected, or at least made better, by lowering and/or dropping the front of the engine some.

We always stringline the car, locate the C/L of the chassis and make the driveline C/L parallel with the chassis C/L. Maintain the offset from the front of the crank to the rear u-joint.