If there is an aircraft junk yard in your vicinity you might try to "shoot" a 'TGT-meter' (turbine gas temperatur). They are selfcontained, so no external circuitry is necessary and measure temperatures up to 1,500deg/C.
I used the TGT-meter of a T-33 for my funbuggy and fit it directly in the exhaust pipe close to the cylinder heads. At full power (with water-methanol injection) the "TGT" was 1,300deg/C.
The extra length of cable (no plugs!) can be wound to a spiral (don't cut. The device is unusable after cutting the cable).
Assuming you intend to use the sensor in an SMD soldering oven it is best to measure on a piece of PCB next to the one to be soldered to keep errors at a minimum.
Boncuk