The piston deck height should be okay. as far as I know chevy didn't really change the overall cylinder block height, they just changed the piston-to-crown length to accommodate longer stokes. so the 307 pistons with the small journal 327 crank and 327 connecting rods should be fine - because all connecting rods share the 5.7" length except the 400's. but i did notice that the 307 cranks had a larger rod-journal diameter, so 307 connecting rods would have to be used in that case (just in case anyone is wondering).

oh the block number is 3756519.

thanks guys