Ron, There is a lot of variations in Chevy blocks. Some have to be clearanced all over and some act like you have an aftermarket block made for stroking. Check with your machine shop because sometimes they will clearance a block for around 50.00 extra when they are doing your other machine work. That works out real well because if you get your machine work finished and then start mocking up for clearancing you take chances of stratching your pretty hone job and not to mention all the shavings that get in the block from clearancing. At the machine shop they do a final washing after everything is done and when you bring it home its ready to put together. BUT NEVER EVER TRUST THAT, ALWAYS CHECK YOUR CLEARANCES ON CYLINDERS AND CAM AND PAN RAILS AND EVERYTHING.

One other point is you mentioned turning a 400 crank down. That's a bad move because it will cost more to do it with the right fillet than a brand new and better Eagle crank will cost. Go with a Eagle or Scat crank. They're both good in my experience with them.