I'm not sure what you mean by "Not sure why 400 ft lb of torque would not be enough for you."? Did I say that?
Anyway, the more torque down low the better. I would not try to set a limit :)
Torque is all about displacement and VE% and CR, most 9 to 10:1 engines with decent heads cam intake and headers are gonna be between 1.15 to 1.25 lbs-ft per cid if you make over 1.25 lbs-ft your your doing really good. Engines between 1.35-1.45 tend to be well put together race engines high Cr 12.5 plus big roller cams and high flowing cylinder heads. Torque is basically the power of one revolution hp is all the revolutions added up. 383 can be revvers since they got big bore for breathing and short stroke for rpm, but are only that if you build them that way most street engines are gonna make peak power in between 4500-5500 depending on the build. If you build for peak power to be between 4500-5000 your gonna have a very streetable .08-1:1 hp:cid, 5000-5500 1-1.2:1 hp:cid ruffly. above 5000 gears and stall become important, which you have. Above that your more into street/strip.
