What would it take to make 1.44 lbs-ft per cid ?

273 said
420 lbs-ft out of a 5.0l is pretty good that's like decent 340 or a mild ish 360, you should have no problem hitting 475 lbs-ft, that's 1.16 lbs-ft per cid that would definitely on the low side for any decent 408.

I think the ft lbs/cu in metric is probably not that important. It's interesting but I don't think it's necessarily a great indicator of efficiency.

Look at the figures of some pretty legendary engines. The number is all over the place.