I cleaned off the loose stuff & there was virtually nothing left. I welded nuts onto the remains of the bolts to remove them.
Surprisingly, the crossmember & the rest of the structures are ok.
The new brackets needed the lower slots lengthened about 0.050" & I put a 3/16" stainless spacer plate underneath both sides.
3 of the 16 fillet welds for the gussets barely touched the gussets. Strength-wise the welds on the other side are plenty adequate for the gussets to be ok.
Being Canadian, the cost escalates for the four parts:
2 braces: $50 US
2 brackets: $75 US
shipping: $60 US
CDN exchange: $43 Tax & fee: $31
(Canadian Border Services fee to collect the $21 harmonized sales tax: $10)
Oh well, that's a small price to pay to keep the wheels from falling off...
I wonder if anyone has experienced a significant failure resulting from corrosion in the upper control arm area...