Oh one more thing- a personal rule of thumb learned dynoing my 557 cam- a conservative mustang brand dyno said my 557 combo made 350hp 400tq at yhe wheels. Which means right around 1hp per cubic inch. If you try to get more than 100% volumetric efficiency (more than 1hp/cid) you are talking about stuffing more air in than the cylinder naturally wants to suck which always involves optimizing big ports & intake, big cam, big headers, big rpm. Which will suck off idle unless you have BIG inches. If you shoot for 425hp 500tq I’m pretty sure you will end up with a fun combo that is respectable at the track. If you really need 500hp then build the milder motor with a concentration on upper midrange power and use forged pistons with a little extra ring gap so you can hit it with a 125 shot of nitrous- best of both worlds and cheap unless you fill the bottle every week.

You can cheat a little with good head porting and prep which can yield surprising numbers with a milder combination.