Jeff - that reminds me so much of the metal repair on my 1980 FJ. Keep going! And when you're all done (after final paint), drown the back side of that cavity with axle grease. Water will get in there and it will rust out, if not well protected on the back side.
Steve H. - KE0KNH
Colo Springs, CO
'78 FJ40, '89 FJ62, '98 4Runner