My take on it is....... unless it was built to fit within some specific set of rules....... or someone took it on as a personal quest....... I look at it as.....why would I do that?
(When a 500hp 408/416 will be easier and likely cheaper).
It’s going to require a fairly high level of effort to end up with a 500hp 318.
From a hp/ci standpoint, it’s like building a 446 at real close to 700hp.
I have built a few 440’s that got into the 700hp range(a bit over 1.5hp/ci).
Those were fairly well thought out builds with good cylinder heads and fairly stout cams.
I’d be happy to follow along though, if someone decided to “go for it” with the 318.