If I was to build a TF 318, I'd shoot for to make around 1.25 to 1.35 lbs-ft per cid preferably above 1.3, and peak power around 6500 to 7000 rpm, eg. halfway equals , 1.3 lbs-ft = 420 lbs-ft and peak hp @ 6750 rpm is about 490 hp, 1.3 lbs-ft is fairly high and should make good tq curve even fairly low down in rpms, add a good stall and deep gears.