I had a 307, in a 73 Nova. Wasn't a fireball, but got right down the road. Mileage was what you'd expect, from a V-8, with a kid on the throttle. Outran a mid 80s Monte, with a 283, one night.
The 307 was a large journal engine, but was basically a 283 bore, with a 327 stroke. It was GM's 1st...