Best Offster Rockers for RPM

JedIEG said
Ok for the sake of this discussion, let me revise my parameters. Let's discuss the best offset regardless of brand to improve the RPM head.
The goal is a steetable head that could go on a ~400cid engine and make 500lbft/500hp

You should be able to get 500 hp with 275 ish cfm with a reasonable cam and cr.