Lap belts are better than no belts.

“They” never got rid of them. “They” replaced them with the safer and more effective shoulder belts. All auto/truck builders were required to design them into their new vehicles.

You should be able to figure a way to get shoulder belts for original side Suburban seats/occupants. The front “jump” seat might be a challenge and would need an awkward rear-bottom seat-base holder/clamp?

I’ll stick with the seat belts.