[LH Lead-Foot]

If you have solid good hood hinges, I would try a few paint sticks at the back center first, then close hood or push down on front with the latch removed for control. The rear lip of the hood should be over the cowl's front flange where the weather strip goes with screws. Remove it, close hood and take measurements every 3 or 4 inches across the back to gauge how much it is out. Use this flange under the hoods back pinch to place those paint sticks first.

As for the side over the fenders, use blocks of wood at the front and perhaps the back later. But place the blocks under the hood at the front, then find something soft, like rigid foam sheet and place a longer block of wood over it to gently push down. Repeat as needed. The braces under the sides of the hood could be hard to work with. Either way, this may transfer warpage across the top of the hoods panel. Cutting a relief slot could help. There is more ways to attempt to do this than anyone could count. I would try bending gently first before cutting and welding.

These after aftermarket stampings are never correct out of the box.

If your low spot is center rear only, start with bending gently first. Cutting and welding, even with cold wet rags nearby, will cause more work than if you can maintain the integrity of the braces and skin fold around them.

I had to replace the tailgate on a 67 C10 and the edges did not match and stuck out on both sides. No way to adjust it out, plus rear bed side around the tail light had no filler when I got it. I had to grind down to metal on the bed sides, add weld rod to shape, then weld in with MIG. After that, I still have misc. dents in the tailgate panel to fix also. Life is hard enough...and then there is aftermarket sheet metal to make more work. Best of luck!