It will cost ~800 more to get an ede in the same range as Brian's RHS head.
Look at the parts that come with them, springs etc. They use the same rockers as any other std LA head. I've bolted on stock, non-adjustable shaft rockers.
OOTB IMM's will make 420HP on a 360 with 9.5:1 and an XE275hl camshaft. Probably real close to the same with a 340.