340 or 408?

Couldn't find a 500+ hp 340 build but here's a little more than you wanted 592 hp @ 7,100/7,200 rpm
460 tq @ 6,000 rpm 400 tq @ 4,000 rpm, 12.5 cr W2 tunnel 263°/268° @ 0.050" solid cam'd 345.

You go a little on everything you get a little less hp.

https://www.motortrend.com/articles/mopp-0205-340-big-block-engine-buildup/

https://www.motortrend.com/articles/mopp-0206-340-big-block-engine-buildup/