How would I disable my range oven's timer?
I have an almost-as-old-as-yours Magic Chef oven, and the igniter and the oven light should work fine with the clock disconnected. Here's how to do it. 


unscrew the back panel to get to the clock. 
There will be two wires connecting to the clock: a white wire and a black wire that's daisy-chained to the light switch on the left side of the top panel. 
disconnect both wires by wiggling their wire clamps and pulling until they come off. 
cover the bare metal ends of both securely and thoroughly with electrical tape. This is very important!  If those wires contact any nearby metal you'll short the circuit at best, and at worst cause a fire-- unintended sparks around gas ranges are a shortcut to a very bad day. 
I'd suggest taping the now-fully-insulated wires to the back of the clock panel so they won't be dangling in the back of the range where it might be hot enough to damage the insulation on the wires.