The pinion being offset some is not a problem at all. The driveshaft will be fine if not parallel to the truck centerline. Here's a tech tip with resources explaining driveline setup, how to measure the compound angle, and how to figure the U-joint operating angle.

http://www.stovebolt.com/techtips/driveline/setup/index.html

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-