This is my first post, so I hate to seem argumentative, but a Lot can be done with a 305, and there are some great parts out there to make them run like a scalded dog. I have a 305 and like the rev range up to 8000 that is available.
The 305 is of course 5000 cc, so there are plenty of good used race parts cheap that are fine for street /show. I took a 327 out and put a 305 in...