[AZKen]

In general, engine swaps are done by taking off front clip. Then placing motor into place to mock it up and check all kinds of clearance issues and solve them. Universal tubular cross members are available for motor and tranny (or perches for motor if you wish). Most any motor will physically fit a 60-66 GMC or Chevy truck. You won't be the first to put that in that. Mr. Matkin is correct, the website is for preservation, not radical modification into a hot rod, rat rod, etc. At least you are not taking out a V6.

Hope you will maintain the look of an original GMC. If you feel uncomfortable in discussing, then PM me and check internet for Chevy swaps. Almost the same chassis, in the engine bay, for a 66. The Chevy chassis had V8's in those years. It's not going to be real difficult to do the swap. You are half way there already.

Please do not post sideways pictures. Fix them on your computer, then attach.