Heres a few:
1978 440, stock long block, Crane H302-2 cam (.518/308 int, .528/318 exh hydraulic), iron 6bbl, 1 3/4 headers, apprx 70K on longblock: 106mph = 402hp at crank on pump unleaded.
1970 440, stock shortblock w 65K miles, 516 heads home ported by me, 1.5 Crane iron rockers, MP.528 solid, 1 7/8 headers, Torker II and 800 Holley: 113mph = 465 crank hp on VP Purple (12.8:1 static)
1968 446(440+.030) KB hypers, ported 915s (also by me but after a lot of improvement on my part...lol), MP.528 solid, 1 7/8 headers, Street Dominator, 750 holley with factory dual snorkel air cleaner: mph = 503 crank hp on pump unleaded
For 400 hp, rebuild it with flat tops at 0 deck, and do basic performance rebuild on heads. no need for porting, dont waste your money on gimicks or aftermarket heads. A hydraulic cam, and headers, and using the factory intake and carb you'll surpass 400hp. Build it right, and later you can upgrade to better heads and cam and really make it fly.