replacing the speed control with a mkV speed control has been done but I think it's a fairly big job. there is a thread on this forum somewhere where someone did it.
From your pics it looks like your cam follower is still in good shape if you can remove the inner bearing race without damaging it.
BTW, have you checked to see if your motor starts and runs in fwd and rev without the belt on before you stick anymore money into it? mkVII motors are rare also.
SS Mark VII(sn 405025), SSband saw, SS 4" jointer, SS Mark V 1980,
Smithy SuperShop 720, Craftsman RAS, Ridgid TS2412 Table Saw,
Delta 12" planer