I'd go 350. 305's were dogs. I have heard that 305's don't really save gas. I don't remember what the reasoning was, but they weren't supposed to run as efficiently as the 350. I had a 307 that weighed in on that being correct. 307 got me about 14mpg and the replacement 327 got around 17 with the same components bolted back up...anyway, 350, more power and gas consumption will be about the same if not better in my opinion.
