80s 350? there were a lot of differant versions during the 80s-----------is it a one piece rear seal ? does it have factory roller lifters? if no rollers-does the lifter galley have the 3 bumps down the middle where the spider bolts down? are the top of the lifter holes machined flat for the dog bones? I would post some pics of what I'm talking about, but other people here have differant opinions about how it should be done----

Also, I would suggest using 6 inch rods as it allows crank conterweights that are better suited for balancing the strokers internally