Broken Distributor Camshaft Drive Gear

I have a 1955 TO-35. The distributor shaft seized and broke the gear in the engine that turns the distributor shaft. How big of a job is it to replace this gear assembly? Is there a cross-section of the engine anywhere? May 7, 2014.

I’ve attached copies of the section on replacing the cam shaft from the TO-35 shop manual. You’ll have to pull the engine and put it on an engine stand in order to turn it over. The engine has to be turned upside down in order to remove the cam shaft. The gear that drives the distributor is on the cam shaft.