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!

What if you have both (318/340) "sitting around" collecting dust and insect nests....the cost is the same across both, gasket set, timing set, cam, oil pump, rings, blah blah blah machine work...etc. then which, all things considered one would you build? (yes there are folks who have multiple engines siting around in their garage).