With that cam, the 1.6 ratio will probably be fine. What are the heads drilled for? The thread size of the studs is larger than the bolts for pedestal mounts. Most X heads come set up for pedestal mounts. So if you want to use studs, you'll have to have a machine shop alter the heads to accept the larger studs, unless yours are already set up that way. If the stock HO rocker arm bolt will screw in you X heads, then the pedestal mounts will bolt on. Also, if the heads have the springs that came from FRPP on them, you should probably have them checked for spring rate and bind - to see if they'll control that cam.