Pioneer Automotive Products, in Meridian, Miss. lists new rocker arm assemblies for the 235, Part # RA-1022 for 1950-58 models, and Part # RA-1033 for 59-62. No prices in the catalog I have, but it's worth a call to a warehouse distributor if you really need a new rocker assembly. They've also go internal engine parts for a lot of the older stuff.
www.pioneerautoinc.com Jerry