Don, over the years I've heard many complaints on sbc starters not lining up correctly be they after market or from the parts store. When I put the 400 in the '62 pickup I swapped the nose cone from the 400 starter with the 283 starter and bolted it to the bellhousing and never had any problems.
Your engine sounds really good and I can hear the need for the baffles. Forty years ago it wouldn't have mattered. As with others I anxiously await it being finished and on the street. It will be a head turner.