The biggest thing is to match parts, Either build it for bottom end power or mid range or high rpm!!! Don't mix a low rpm cam with a high rpm intake Etc, Etc! Same with your drive train! Match your torque convertor to your flash torque, If you don't it will eat up your torque! final Gear ratio and tire diameter can do the same!
The next is to blue print, Stock Or High performance it makes no difference a good blue print build will bring power out of hiding!! If you set one rod bearing at .001 set them all at .001 (or as close as possible) If a manual says rod bearing clearance .0005 to .003 that means .0005 is new engine tolerance and .003 is just at the wore out point and passable! If you get a bearing reading of .0029 across all the rod bearings when assembling you just built an engine on the point of being wore out, same with ring gaps , mains, etc. a good balance helps a lot! Anything that is parasitic that you can reduce the drain of H.P. like a large heavy big pitch fan, water pump, H.P. draining alternator, heavy pulley's, Heavy dope, heavy oil ETC,ETC! Don't install a high pressure oil pump if its not needed the higher the pressure the more engine torque and H.P. it takes to drive it! Too high an ohm plug wire can rob H.P.! There are many things you can do to bring out H.P. and torque! Re curving the distributor, advancing or retarding the cam, lightening the valve train, The right headers, and porting or not porting depending on RPM and scavenging ability ( sometimes small ports perform better then large) in some combinations! Reducing internal friction like oil windage, Crank case ventilation! Etc,Etc, There is much more Like the weight of the car and whether you need high torque to get it moving or high rpm for speed!