There is no need to go to chrome shafts because the factory shafts are hard steel.
These engines lasted for years with factory shafts, zero problems. Thermal expansion is not a problem @ 0.003" clearance with both parts expanding together & both have the same expansion rate.
The most important thing has not been mentioned. Which is NOT to over torque the shaft mounting bolts which could deform the shafts & cause the rockers to bind.
