318 and 360 small block question

i'll follow up the question from @318willrun with: what are you starting with? do you have a motor at all or just one that's clapped out? do you want headers and a 4bbl carb and it sound mean? what are your expectations: does it have to get really good mileage, do you need enough vacuum to pull power brakes, do you want it to idle sewing machine smooth and quiet?

all of these are considerations.

@TT5.9mag had a wonderful suggestion of 5.9 (or 5.2) magnum motor as a base.

really you can't go wrong with either motor. the 360 has a slight edge in making power because of the extra cubes, however with the power numbers you're most likely looking for the added cost of a 360 probably wouldn't be worth it.