Broken rockerarm Generac Generator

Do you have the tools to do a leak down test? Or at least a compression test. If the results are good, you can probably get away with not pulling the head. The bent pushrod is more concerning than the broken rocker arm. A rocker arm can break from a manufacturing defect or poor lash adjustment. To bend a push rod the valve train had to hit something solid. Hopefully when he welded the rocker arm he messed up the angle and just bound up the valve spring. Stand a decent chance of no valve damage as those are fairly low compression engines. I would replace the valve retained on that valve for sure because if it was spring bound there was a lot of stress on the retainer and you would not want it to drop the valve a couple months down the road. Might be tempted to replace the spring as well. Run the lash at the loose side of the range to start. Run it through several heat cycles (run under load for 30 minutes then let completely cool down) then set lash to specs, preferably cold if they give hot and cold specs. HAving the lash too loose can lead to broken rocker arms. Might have been the root cause of the original failure.

EDIT:
On my Onan, the lash spec calls for .005 for the intake and .013 for the exhaust valves when cold. I don't have the specs for a Generac.