I dunno about drilling the hinges for lightness. You’re gonna save, what? The weight of a couple of #2 pencils? 
The engine cover is held up by the hinges at the front, and by the latch pin in the cover at the rear (plus any buttons or weatherstrip that might have been installed between the cover and body).
Front of the cover can be lowered by turning the hinge firewall side bolt holes into slots, as Wolfgang alluded. Then, when loosely re-assembled, put a cardboard spacer between the cover and body flange to set the height you want, then tighten the bolts at the firewall (just use a pair of vise grips on the engine side of the firewall on the bolt head to hold the bolt while you tighten the nut on the back side).
Back of the cover: is held up by the pin going into the latch Jaws. Easiest fix is to slot the latch mounting holes in the bracket holding the latch, then move the latch down via trial-and-error til you get the cover where you want it.
Hood: If the rear height of the hood looks level, open the hood and see how the hood is attached to the hinges and then, as Wolfgang mentioned, slot the holes in the hinge arms that the hood directly attaches to. Re-assemble hood to hinge and get the bolts slightly tighter than finger-tight, then see how it looks when closed and adjust it (gentle taps or nudges) back to where you want it, but beware, you’ll probably have to slot where the front latch pin attaches to the hood if you’re moving everything back more than 1/8” so both ends of the hood will line up.