The quick answer may be that these are handbuilt early unibody cars with variations. Note that some have more of a radius at the front-most corner (where the quarter meets the top of the nose piece) than others...
Trial and error just about covers it. (for me anyway)
Initially, I tried to make sure the hood was pulled as far forward (or up) before I closed the hood, to ensure the front of the hood wasn't bound up and mangled. Obviously the back (windshield) end has some room for error and won't smash the windshield or similar.
I snugged up the bolts enough for them to hold the hood in position, but not so tight that I couldn't make small movements with the hood lowered. The really difficult part is finding the "sweet spot" where the bolts are tight enough to hold the position but loose enough to be "persuaded" into the correct placement.
After I slowly lowered the hood down, it was easy to eye the gaps and figure out which direction the hood needed to go. The hard part is adjusting the hood without scratching or otherwise damaging the paint. I used a variety of duct tape-covered screwdrivers, plastic joint compound knives and spatulas and rubber mallets to get the gaps the same around the hood.
It may be very helpful to have a couple of assistants (I didn't) and I also used a box to keep the hood open 1/2 way, giving me enough space to tighten and loosen the hood bolts when searching for that sweet spot.