BB for SB...Your opinions please.

Personally, I think you would be happier with a small block, but that is just me. I have had both and the small block is enough power. The 440 will either roast the tires in all gears or will be detuned to the point that a small block will be equal to it without the weight or fitment hassle. You can get a pulled 318 for peanuts on craigslist, 360 for more, but a 318 in a light car like yours can be fun too with the right gear.