your problem will be the solder. it will fail due to thermal stresses. the board is going to grow due to thermal expansion more than your lead frame of your part will and the solder is going to shear out. using something like Indium 182 (basically 20K tin/gold solder)which is about the strongest solder there is on the market for high temp applications will help, but you need to look at controlled expansion ceramic board substrates too to cut down on the shear loads developed. We had that very same issue for downhole electronics instrumentatation. we realized that using through hole instead of surface mount as well has indum 182 and ceramic board materials (raychem was the supplier we used I believe) were all necessary to get decent life out of the assemblies at elevated temp. gluing your part down will keep it stuck to the board (maybe) but it won't do anything to improve your solder connection reliability, you'll get cracks and intermittant open circuits due to thermal stresses. we had several SMD prototype boards that after thermal cycling all the chip resistors and chip capacitors fell off due to sheared out connections. SMD is NOT a good technology for high temp.
