Is building a stroked 318 better than a stroked 340/360?

I would go with a 360. There is no replacement for displacement. But that is me. You may not care about the extra 42 cubic inches between a 318 and a 360, and 42 more cubic inches will be about 63 HP at about 1.5 HP per CI. If you don't care about the extra CI, then go with the 318. I think it would be a hoot to tell people my car had a 318 and then lay down 100 feet of rubber in the burnout and run a 12.00.