X-heads enough for 408 stroker?

If you compare costs you will find it slightly cheaper to have a performance shop do a "stage II" porting on them, a good valve job, good performance valves, and properly set up. It's easy to reach the performance level of the RPMs that way, but you still have the weight and open chambers. Generally the RHSs are about $200-300 more to get properly done and ready to use, and RPMS are about $200-400 more than the RHS.