I would look at screw in studs and stamped steel guide plates, because that crane cam will have a bit of lift and will / could work those press in studs out. While your at it stick in a set of long slot rockers wind the motor over by hand to with the plugs out and with a straightened paper clip and 1 stick it between the rocker and stud for clearance and 2 between the valve spring coils to check for coil bind as check to insure against catastrophies.