I dont know about the WP,
But the gas stove would be fairly easy...but kind of involved...on gas stoves of this vintage the flame reduces in size to control the temperature, increasing and lowering during the baking process, this adjustment is critical, for if the flame doesent reduce enough, the oven will get too hot, on most thermostats their are 2 adjusting screws, one for the pilot, one for the bypass,the pilot should look about like a Zippo lighter when lit, lite the oven and set at 400...let heat until it cuts down, then turn the dial to about 200 or so, open the broiler and look at the flame, it should be tiny beads of flame around the entire burner, if not, pull off the knob , use a screwdriver on the screw marked by pass..adjust CAREFULLY until just tiny beads of flame burn around the entire burner, then put a thermometer on a center oven shelf, turn back to 400, leave about 30 minutes, quickly open the oven and observe temp...on most old Robertshaw or Wilcolator thermostats, under the knob is an adjustment, usually you loosen 1 or 2 tiny screws and raise or lower the temp...dont be in a hurry, let oven operate 20 or so minutes between adjustments to make sure you have it just right..
