The "Throw Away 318"

Very true. The bore size is a big factor & a huge help in power making on any engine size. This is one reason the 340 is favored above all.

If I was rebuilding a 318 to perform, I would move away from the stock bore size as much as possible to get the head to breath better.

If it were easy to do…..
And I was under a cubic inch rule, it would be maximum overbore and a destroking to maintain the 318 CID rule.

The bottom line is, plan accordingly.