One of Andys engines ran the Comp HXL lobe intake profile and the HXX exhaust. I though the size was in the 260's? My 499(500) stroker uses the HXL lobes intake and exhaust, but I think that might be too agressive on the exhaust side? I don't know exactly the difference is on the HXX exhaust lobes (don't have one to measure), but I think my combo would be better with a bit slower opening profile, and maybe just running a 1.5:1 rocker on the exhaust side.