Some have a long single mount, others are individual, this allows you to shim intake and exhaust rockers to different heights for the best rocker geometry. I haven't measured a late six but Jessel shaft rockers ride in a saddle. You would have to machine down the rocker bosses and tap them for the bolt that holds the saddle to the head. The stability of the saddle would be limited to the surface area left on the boss. You would have to check to see if a saddle with the right dimensions is available. After all is said and done, the cost, in my opinion, is too great for the results. Big block rollers and screw in studs are fine. Arm
