if all you are looking for is a 400hp sbc 400 then dont bother with forged internals. if you can find a complete 400 (good luck!), tear it down get what ever machine work needs to be done to the rods, crank, and block done. buy a set of 18cc dished pistons, a mildly price set of 200cc runner/ 72cc combustion chamber steel heads (should put you around 9.4:1). get a hyd f/t cam with somewhere around 220-232° duration at .050, dual plane intake, 50-60k volt cheap HEI distributor, 750 vacuum sec carb, $250.00 set of headman headers, 2.5" exhaust and some decent mufflers. it will want atleast a 3.73 gear in a truck if not a 4.10 and it will probably want around a 2800-3000 stall.
bam! simple 400-430hp (easily) 440-460tq (again easily) motor that will be rather easy on the pocket.