That rear seal modification will definitely be part of the upgrade. I'm in the "dreams and schemes" phase of planning a modification to the GMC 228-302 engines to use a modern 2-piece neoprene rear seal instead of the rope seal they were designed to use. That will require some machining to the back of the block and the rear main bearing cap to use a bolt-on 2 piece seal holder. I'm also in the process of designing a drill guide fixture to put pressure oiling passages in a 216 spray-oiler crankshaft.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!