Scream'n 318 ?
My 273-4 would regularly exceed the 6K of the lousy stock SW tach that came with it. Not sure if the tach was just slow reacting but I could bounce the needle past 6 and it still wanted more. stroke is identical in a 318. No reason it could not rev like a "tight little 273" that everyone gets a warm feeling up their leg for. you want a quick 318, 4+ gears in the rear and 7K redline, just get good rod bolts.