sMike was right. Located the split, clamped as best I could and welded the split. Then put a 1" bead on either side of the split, 1" bead at the other four "corners". Ground tooth valley clear. Realized that part of the bendix would want to occupy the same space as the weld beads. Grabbed the grinder and trimmed the top of the beads. Installed old bendix in new starter, installed starter, applied power and crank rotated! Reinstalled spark plugs and tried cranking again; still OK. Bendix still bangs on the split space but I'll get over it until it breaks.
Installed two missing plug wires and attempted to fire; no joy. Checked spark; none. Checked coil terminal; no juice. Vetted ignition switch and it works opposite of every other switch I've had. Rechecked coil terminal; good. Replaced all plug wires and rechecked spark; good. Got my nearly empty can of ether and went to work. The rest of the can yielded a cloud of blue smoke and a couple of pops of exhaust!
Promising!