I only had 2 issues w/ my KB hemi block. 1st was a couple of the lifter bores were a little tight. Easily fixed w/ a light honing. 2nd was the front counterweight on my 4.5" stroke Callies crank actually hit some of the webbing in the block and needed a little clearancing. Not a big deal at all, but did surprise me. Glad I caught it in the mockup stage. The rods all cleared just fine.
Naturally there was a lot of clearancing to be done for the pushrods, but that's to be expected.