it would be cheaper to find a used engine, vs the new crank, or machined crank, and block and new bearings.

if it was a older 350 you could get away with what your talking about, these blocks tend to warp, so with out machining the block, 99% of the time they dont last long.

if you cant find a l67 or l32, but can find a n/a block, then top swap it with your engines parts. get it tuned and your set.