We used to race a dirt sportsman car with a 320 cubic inch limit. Our engines were 283 blocks with the 327 crank, Yes the same dimensions as a 307. We also ran .060 over and I think that was a 316-317 c.i. It was a pretty potent combination. The stock 307 had a pretty bad rap for being a serious dog. When I was a kid my dad had a new pickup with a 307 4 speed. It would go 100 in third gear and only 85 in fourth.lol.