Mine was only a standard 55g.
Broke the center brace on my oldest dirt tank, I wanted to pitch the old scratched up thing but I can't LOL. It's the poster tank for those that say dirt doesn't last so I have to keep it.
1/8" 316L bare tig wire bent 90° to wrap the frame front and back at the exact measurement then glued in place is plenty strong.
Anything over 1/8 thickness is overkill but flat plate warps badly in narrow strips is why I used the wire.
1/4" x 1/2" is a bit bulky but stiff enough not to warp.
2 flat 90° plates for clamps and a threaded rod in turnbuckle arrangement is easy too.
If help fails to appear shoot me a PM. We will get measurements taken within 1/32" that easily transfer and I'll make it up out of 1/2" if that helps you sleep at night.