Getting an Oxy-Propane flame adjusted down to a fine enough point to shrink with might be a challenge. An acetyline rig with a #0 tip allows me to heat an area about the size of a dime or smaller red hot, then quickly quench it with a water-soaked rag. Shrinking is mostly used to correct "oil canning" where the dented metal has been stretched beyond its natural "memory" elasticity. Rough out and "metal finish" most of the dent out with a hammer and dolly, then shrink the places that refuse to go back to their original contour. Resist the urge to heat before you do the necessary hammer and dolly work to achieve a contour that's very close to original.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!