Unfortunately I didn't learn, what I was taught

I'm making a stand for my tabledrill, welding a 10"x13"x 5/4" plate of mild steel to a 9" pipe with a 1/4" wall thickness
I got too excited and kept on welding, instead of backtracing and changing spots, and the plate got too hot and warped.
Kicking myself doesn't seem to help, so I've decided to try and reheat it on the other side. I intend to use a gas torch with a narrow flame on the opposite side of the weld. I was hoping someone could give me a pointer as to how hot I should make it. I do have an infrared thermo reader, or I can use a redhot scale.
Happy Holidays everyone