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

Well I'm pretty sure a junkyard 340 would take 14.5psi for a SHORT time also.
Now take a running junkyard 5.2 magnum get the rods and crank rebuilt probably hone the cylinders depending on core shift and a few other factors. Freshen up the heads . Then they run 14.5psi and live KRC back in the day done that along with a lot of other places. And the stayed together.

You don't have to spend money on a bunch of money on exotic parts to make a solid engine. But the stock parts need to be approved and within spec. You can make a 400hp 318 with stock rotating assembly that actually has a long life span.