Why do you want a shaft mounted rocker system? What will it do that stud mounted roller rockers will not do in an inline six? As far as I know only engines that see lots of RPM, like small block V8's operating in the 8000 - 14000 RPM range benefit from this kind of valve train stiffness. Do you plan to exceed 8000 RPM? If so then you may want to contact Harlan Sharp - he has made me custom shaft mounted rocker arms in the past, but even then these were only roller tipped aluminum bronze bushed rockers, not needle bearing pivot ones. Good luck.

FORD 300 inline six - THE BEST KEPT SECRET IN DRAG RACING!