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

dollar for dollar...i think 318willrun is correct. It's quite easy to find a good running 318 for next to nothing. Add a cheap stock cast iron manifold,a used carb that may need to be rebuilt and cleaned,and a small cam . You will have a nice motor that will be more than fast enough to be fun in a light A body..(especially an early one) for really next to nothing!
a good running 340 does not have next to nothing in it's cost.