Spoom, I totally see Riviera too from the top-side view.
However, when I look up Riviera hood insulation the asymmetrical bracing doesn't match anything I looked at.
By the 70s many (GM at least) had gone to the one-piece insulation. Some Thunderbirds used 7 piece in 60s --but searching "7 piece hood insulation" didn't solve the riddle for me. But then I am assuming this hood didn't have a one-piece covering everything.
I looked up some AMC, Plymouth and so on... front lip of hood goes over the grill is tricky to visualize (i.e., 69 Chevelle has a panel in front of the hood, 70 doesn't) and you can't just say "oh that was only cars in 63-65" although that may be the best range.
The hood dimensions would help a bit (i.e., it kind of looks like 66 Corvair too, but then that wouldn't need hood insulation).
Watch... it will be from a 70s Japanese car. Fun topic.
I’m seeing GM too. First thing that popped into my head was a mid-60’s Pontiac w/o the GTO faux scoop. Maybe a Chevelle but it doesn’t look like a model year that had a header panel. And kinda thinking there should be a vestigial hood ornament or emblem on the spine in the middle for those.
Pepper might be on to something with the Corvair but I also see what looks to be a liner clip. Hard to tell but maybe some remnants of that GM blue used in those days too.
I also agree that dimensions or a little more scale would help.
Looking at it again...
-Isn't there a tiny spear of a hood ornament?
-is that adhesive register marks and/or mount clips outside of the areas contained by the braces, that is to say: this hood had a one-piece style insulation?
Good points. I didn't do any research, just tried to think what pointy ones I could remember that rolled over to the grill opening. By the 70's a lot of cars had fronts that surrounded the headlamps & grill, with the hood being a "hatch" bordered on front & sides with other body parts. It looked similar to my '63 LeSabre, so I rounded up to a '64 Riviera or maybe a Wildcat. (Looks like the mystery's been solved)