just try slackning all the bolts off a little to give you a little wiggle room and then tighten them up when you have all the bolts in. was the truck ever smacked? but what is different between the 350 that you took out and the 383 that is going in? anything?
ron

http://s908.beta.photobucket.com/user/padresag/library/turned%20works
http://s908.beta.photobucket.com/user/padresag/library/furniture
and a little history of where I come from
http://forum.woodenboat.com/showthread.php?156542-old-boatshop-in-Steveston