I would try and weld the crack itself, grind it down smooth, then weld a plate over the fix using 1/8" and make < > shaped ends to get as much weld area you can. Drill holes in it if you want to make rosette welds if you want. If the frame is curved in that section weld 1" then heat the area and use a hammer to get the curve in the metal. Keep going 1" at a time.

No reason to use thick pieces of steel the frame is only around 1/8" thick.

I wouldn't use bolts if you can weld it.

CHRIS
98 Amigo, 92 Pup

need a pickup 1st gen fuel level sender