Everything I read says to stay conservative with cam selection with vortec heads. In a 400 sbc RPM intake, 9.5-10.0 comp XE274, 750 carb You are well over 425 HP and 500 FPTQ.
And it doesn't need a ton of service and is dependable. In a 3000 to 3500 lb. car or truck the thing will scream.
Stay conservative with stall speed and rear gear selection.