[dsraven]

if the cam were drilled and tapped for a good quality threaded stud to be screwed in, a guy could use a couple of large greased up washers (larger in diameter than the hole in the middle of the cam gear), so they slip on one another like a thrust bearing, and a good quality nut to bear down against the cam gear and then when the hot gear is installed on the cold camshaft an impact gun could be used on the nut to help ensure the gear is all the way home. use some thick grease to retain the spacer ring. I think the gear bottoms against the ring that is between the gear and the cam, its been a long time since I was inside a 216 or a 235 so don't take my word for it but it seems logical that the ring back there is slightly thicker than the thrust plate is so that a clearance could be maintained when installing the new gear up tight against the ring. getting the old gear off, the way where you destroy the old gear, may not be as hard as you think because the gear is likely hard so it could be convinced to split possibly. if a stress line were ground in the gear face from the keyway to the outside and a makeshift nut cracker were made you could possibly get it to crack from the outside to the keyway fairly easily. then removal would be way easier. of course you could always try heating it up fast as well, like with a good sized torch, while a puller is used to supply some force to help it want to move
just a thought.
the other thought I had was to get the old cam off, whether you cut it off or cut partway through and somehow break the rest off, but anyway, get the old gear off without breaking the thrust plate. the thrust plate is likely quite brittle so be careful. then drill and thread the cam to the same thread as a power steering pump pulley removal/install tool. then use the power steering pulley tool to assist with the preheated cam gear install. make sure you have help and everything set up first before you start heating the cam gear.
just a thought that may or may not work for you. trying to figure a quick and painless way to get that steel plate off without taking the valvetrain out.
what I have used for the lifters at times, should it come down to pulling the cam, is some good old fashioned wooden clothes pins. push the lifter up and slip the clothes pin over the stub that the pushrod connects to. use the old fashioned ones with the little spring on them not the more modern plastic ones. get good quality ones that aren't gonna snap in pieces due to the wood being from a poor source and try for the larger ones if available. otherwise, push them up, clean with brake cleaner, dry and duct tape from the top side. this is usually a very short term hold as usually some oil gets in the adhesive from somewhere and soon it lets go. then when you take the tape off clean the lifter so there is no adhesive on it anywhere. another thought may be to push the lifter up and install a short length of tight fitting hose over the lifter and keep it in place with a cable tie tightened on the hose
from what I have read during my quick search on 216 cam gears the reason some of the timing gears were replaced is because the oil passage that feeds the squirter for lubing the gears gets plugged up so no oil reaches the squirter. another tip i learned is that the aluminum cam gear makes for some extra noise when running. the reason why they still sell fiber gears i guess.
anyway, keep us posted with how it all goes and, of course, we will be needing pics.
we're a needy bunch