Maximum Performance N/A 383 build. Input wanted from engine gurus.

If you get peak torque around 1.3 lbs-ft per cid = 505 lbs-ft x 90% for roughly the torque at peak hp = 455 lbs-ft, 600 hp x 5252 / 455 tq = 6926 rpms. If you can get efficiency higher like 1.4tq:cid 600 hp = 6431 rpms less efficient obviously higher rpms.

Heads 290-300 cfm can obviously make 600 hp but I'd be more comfortable trying to get 600 hp out of 320+ cfm heads.