Another factor with RHS heads is that for some reason, some brands of aftermarket rocker gear seem to cause unacceptable rocker geometry. you'll never get that with a factory head. (excluding T/A heads, of course)
There are rockers that fit well on stock heads and others that have horrible geometry issues. Not to mention the constant battle with retainer/spring to rocker interference that happens with many including... are you ready... the factory 273 adjustables!
He needs to pick the direction he wants to go. Some like x/j, some ede, some rhs... how about some w9's just for fun!