X-heads enough for 408 stroker?

I had a 408 with cast crank, Eagle H beams & Diamond Flat tops (12:1). Had a flat tappet cam 260/268 @ 0.50 or about that. Had 2.02/1.625 valves in ported J's. Had a 1.50 60' and ran a 11.21@121 with 3.55 gear in a 3200lb Duster. I think if it had not been laying over on the top end from a bad carb it would have been much quicker. Never got to tune it much after that lost it in Hurricane Katrina. I think if you run those X's you should at least install some 11/32 stem race type valves and at least blend the bowls and gasket match them.