I can tell you the way to build the 302, I did for a circle track car many years ago. Guess what the 327 block is a 4" bore same as a 283 bored .125. So why bore the block to death when you already have the block? Put the 283 crank and rods in the stock 327 block with 283 pistons .125 over. You have to have the 327 small journal crank block, because all 283's have the small journal crank. The pin height in the piston makes the difference, not the rod. Best motor I ever had and is still running 30 years later. Back then the 283 bored .125 over was common so pistons were everywhere, I read how GM made the original 302's and came up with this idea. I just bought a 67 El-Camino with a 283 and am looking for a small journal 327 block. Not so easy now, and the guy I sold the motor to said it will never be for sale again. So stock bore 327 block and 283 crank with 283 pistons bored .125 over. Has to be 283 or 302 pistons only.