['68OrangeSunshine]

The bumper holes were cut in the Late '70s, when used parts for domestic trucks were rediculously cheap by today's standards. A used painted bumper was less that $20.
I bought my '68 C/10 Stepside in 1973, when my '61 Mercedes 190's 4 banger engine blew up [operator error]. I was tired of paying high prices for imported auto parts.
I first had the chromed custom-cut bumper and fog lamps on the pickup when I decided it pulled too much juice. I switched back to the white painted OEM bumper. I stashed the chrome unit. Years later, after whacking Bambi's Dad, I remembered I had it and it went on Old White Fang, the Suburban -- fogs and all. I still have a banana-shaped '67 white bumper, and a white GMC bumper with the curls under the grille parking lamps, that I got by mistake, before I had a GMC. Bumpers were dirt cheap. Fenders $25. Doors $50.
Tailgates & hoods $100. Then came the internet. By the late '90s Arizona was ''fished out'' of cheap clean sheet metal. All went North and east. In '99 I had to roadtrip to the Bay Area for Blazer parts. Now driving my Stepside downtown, I have to watch out for all the chollos eyeing my rig hungrily as a rolling fortune in rare spare parts still on the hoof.

Regarding your kangaroo-katcher: If you did some torch surgery and moved the main uprights inboard one strake, and build longer eye hoops -- maybe reinforcing them with a diagonal steel strap strut 45* from bottom to lower end -- you might make clearance for all the headlights. I notice the grill guard in post #10 has wide eye loops for any GM truck.
That may weaken the structure, though. I'm no metallurgist/engineer.
Have fun.