Take a deep breath....
It's nothing that can't be fixed. At this point you've lost very little....maybe the cost of the powdercoating that will need to be re-done, but that's a small price to pay. This is a safety item, and it's protecting you and your families' lives... that's worth a lot.
The simplest solution that I can see is to put a bar between the two bars that run front-to-back on that cage. Basically create a "square" when viewing it from above. That one bar will address the most glaring issue with the current design, which is that nothing will prevent those side bars from simply bending into the passenger compartment in a rollover.
From that one change, you can decide how much more to do....most people would tell you there's still quite a bit that needs improving.
Suggestions:
1. Put an X-brace across the top of the cage to triangulate that "square" shape that you created by adding the one extra tube that I suggested above.
2. Add an A-pillar structure to connect from the existing cage to the front windshield pillar areas. If you roll over, the existing hoop might protect your head, but there is nothing to prevent the windshield from collapsing down onto you. This basically converts your current 4-point cage to a 6-point cage.
3. Triangulate from the existing B-pillar from each upper corner down to the floor. This is a tougher one, because it WILL affect ingress/egress into the backseat area. Ideally, you'd run a bar across the floor directly behind the front seats and bring the two angled bars together in the center of the truck on top of that floor-bar. The intention is to prevent that main hoop from collapsing sideways in a rollover.....if you look at it now, it's basically a square shape (when viewed from the back of your truck) and a roll would probably just push it into a "parallelogram" shape...
4. Tie the cage to the frame underneath, or at least to plates underneath the truck. A cage that's only bolted to the sheetmetal of the truck isn't going to work very well.....more like an old-fashioned can opener. The forces will simply punch the cage right through the floor at the existing mounting points. Most of these early trucks have a lot of hidden rust in the floor areas (especially the front footwell areas) so it's even more important to KNOW that the cage is bolted to something equally strong.
You can get this corrected for a little extra money..... rarely does anyone get everything perfect on the first attempt, so don't beat yourself up over it. But the lesson is also to do your own research and don't necessarily trust a so-called "expert" unless they have relevant experience doing the type of fabrication you are asking for....
