Yes once you go under 340 cid and a 4” bore physics goes out the window, and a engine can’t be built to make hp.
Just cause people don’t doesn’t mean they can’t, 400M we’re considered boat anchors until they started sweeping up the competition in engine build competition, one of the builders on this site got 473 hp out of a 273 @ 7900 rpm, with ported EQ heads. Don’t understand how people are ok with 340/360 making power but as soon as you do those same things to a 318 it can’t happen ??
and yes rumblefish360 7500 might be a tad high there’s 302 and 5.3ls getting done by 7000 rpm, went with worse case scenario.