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/
| RPM | Ft/Lb | HP | BSFC LBS/HR |
| 4000 | 400.3 | 300.9 | .392 |
| 4500 | 421.6 | 361.2 | .385 |
| 5000 | 459.0 | 437.0 | .373 |
| 5200 | 459.3 | 454.7 | .381 |
| 5400 | 458.0 | 470.9 | .379 |
| 5600 | 454.9 | 485.0 | .392 |
| 5800 | 449.9 | 496.8 | .396 |
| 6000 | 460.1 | 525.7 | .415 |
| 6200 | 454.0 | 535.9 | .435 |
| 6400 | 452.0 | 550.9 | .438 |
| 6600 | 457.7 | 575.2 | .436 |
| 6800 | 446.8 | 578.5 | .442 |
| 7000 | 439.2 | 585.4 | .457 |
| 7100 | 437.7 | 591.7 | .550 |
| 7200 | 431.6 | 591.6 | .586 |
| 7400 | 414.4 | 583.9 | .552 |
| 7500 | 407.1 | 581.4 | .536 |