If you have a slapper or spoon to use as a dolly you should be able to flatten the dents by putting the spoon ( or even a piece of bar stock) on the low spots and lightly hammer around them. That’s known as off-dolly and minimizes stretching the metal.
A jack screw like you mentioned would work too, but you’d probably have lots of trouble repositioning it. You’d still want to hammer around the low spots.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.