Yes, hillclimbing on the Wasatch range in my '67 scout.
I think I was low on gas & it got so steep the pickup in the tank started coming uncovered. Or maybe the fuel pump was weak, because the engine pinged a few times and died.
(BTW, short wheelbase vehicles do not steer well in reverse at speed, even with reverse engine braking, Also, Scout brakes are not self energizing in reverse. It was a wild ride down.)
As for your friend's car, does it have vacuum advance or just mechanical?
I might go drive it around with a temporary vacuum gauge on the wiper hose & watch what the needle does on a hill.