Iv read a couple of accounts where ppl claim to have bores a 318 to a 340. There was a guy on fb swore that he had one even read it on another forum. I'm a little hesitant to believe it. But I'm not going to call anyone a liar. One guy said he tried it on several different blocks at least a dozen and only found one that made it and didnt crack and it was a 67 model block he claimed that only pre 68 blocks should even be considered and even then it was a long shot. But he claimed that he did it!
If you make the road trip you will have to stop by and chat for a while you will drive right by me on the way to nc!