Sorry to revisit an old debate but...

Spend some time over on the slant6forum if you haven't already. Lots have made the swap from /6 to 318 and that works out fine for most. But there are ways to help that old slant a little. There is a nice "how to" on grafting an '80s GM throtle body fuel injection system on to the slant 6, or running two 2bbl carbs or even one guy runing two 4bbls. Supercharged or turbos. Someone was running the turbos from Omni O24's on his.