I'm trying to figure out at what point in the assy was the engine bay painted semi-gloss black. Were both sides of the radiator support painted semi-gloss black in this process? This would be on my black '66 Hertz.
Yes both the front and rear face of the radiator support were normally painted as was the front cross member
Easiest way to think of the application of the black on the engine compartment walls for me is that from the cowl to firewall pinch weld down ward and forward. And on the outer surface of the inner fenders - from rear spalsh shield attachment point on one side to the one on the other.
The application, since little or no effort was made to bend over much
by the painters did produce shadows often/sometimes on the rear surface of the radiator support right under the lip, in the pockets behind the hood bumper brackets and under the inner fenders where the lip is formed - at the fender attachment point
Insides of the shock/front spring pockets often got little paint right at the very top and the forward and rear surfaces of this pocket that would surround the coil sprung may be a little thinner than the back surface but they were painted black normally leaving no visible red oxide
The black at the rear of both inner fenders/frame - the wheel well was blacked either by direct application or very heavy overspray all the way down to the frame rail typically
Not much to show in pictures - everything pretty much gets black that one could see from standing above, to the side or to the front on the majority of cars .