Digimon - To level the edges... get a pack of sheets of self-adhesive sandpaper (120 grit.) Find a perfectly flat surface like a countertop and stick four sheets of sandpaper down in a large square shape on the counter-top. Set the drum down on the paper and start rubbing it (by spinning it left and right) on the paper. Check regularly during the operation to see if the edge is dead level all around by placing a flashlight inside the shell and then inspect the edge from the outside looking for light leaks. If you can't see any light leaking through from inside, the edge is dead level.
A recommendation if I may... Use the 45 degree cutter to make the back cut on the reinforcement rings and then use an 1/8th inch round-over bit to cut the outside profile. If you put straight 45's on those shells you'll make them sound like modern drums. Those vintage shells with a nice fat round-over will sound resonant and warm. The 45's will create a different sound, more attack and projection. Remember to stop the router cut about 1/8th" away from where the cut begins. Finish it off by hand with a file. If you run the cut completely around, you'll only keep cutting deeper and deeper into the shell. Remember to stop the cut 1/8th" short. After you recut the edge profile with the router take a piece of sandpaper and buff back and forth along the edge to relieve any hard/sharp spots where a head might hang up during tuning. If you finish the edges with butchers wax and a good rub with 00-00 steel wool, they will be smooth as glass when you finish. The drum will tune up easily.
Fun project to watch, good luck. Can't wait to see them all done.
John