500+ hp six pack build is easy and doesn't need be expensive either.
It's a long read.... we Machined/Built and Dyno tested 2 identical 440's
and we used a 4 BBL and Stealth Heads for the factory appearance, but go have a 'Boo through this for a few ideas on the basic engine build, the six-pack would still get there easily.
The 2nd one used just a Comp cams XE284H and made 545hp @ 5,500 rpm with 562 Ft/Lbs @ 3,500 rpm
We still get LOTS of requests for these.... alas they aren't money makers for us and NO time.... but very capable little budget engines.
STEALTH Head Update.... A "lowly" 440 Street Engine