Back when these engines were daily drivers, it was common practice to swap a stripped cam gear without removing the camshaft. Break the fiber gear off with a big pry bar, and split the metal hub over the woodruff key with a hammer and chisel. Then use an air powered hammer to drive the new gear on after heating it in an oil bath or CAREFULLY heat just the hub with a torch if the replacement gear was the fiber type. Aluminum gears virtually never failed, but they could be removed by drilling and tapping a couple of puller screw holes in the old gear. The more careful guys would remove the fuel pump and have a helper pry forward on the camshaft through the fuel pump hole to avoid damaging the thrust plate while installing the new gear. Someone who couldn't replace a timing gear before lunchtime probably wouldn't have a job the next day!
Jerry
