Today, dollar for dollar, is the 318 faster than the 340 ???

Of course! Keep resale out of the equation. This is all hypothetical since we all know you'd be much better off with a 360 than a 318.

What would you spend the $3k on for the 318? By the time you sprung for a decent set of heads, you'd be almost even with the 340 (cost-wise) and still 22 cubes short.
I'm thinking heads, pistons, cam, 4bbl. I'll take good heads over 22 cubes. But that's just my opinion.