Looks like the two sides could be joined with bolts.

 

Repair, or replace?

It has stress cracked, bolts alone will not do the job. If you can cut a piece of flt steel to fit in there and drill holes to use 4 bolts at least to hold it together, that might work. Better fix would be to weld the crack, grind it smooth and weld a smaller piece of plate over the crack.

Yeah, a small piece of angle iron across there and bolted through the cable housing bracket itself would fix it right up.

 

The problem will be getting the holes drilled!

 

You might get it done in the car with a right-angle drill and a short bit. But you will probably just have to remove the assembly. 

yeah seen this twice.  pull out the box and weld/reinforce

Seen this many many times. As mentioned by gloyale - remove and repair. “Sew” it up with a mending plate of your own design.

 

This is a very common issue going back to the 70’s cars and as long as they use the same type of pedal box.

If you change cables - buy new - be very careful not to by aftermarket crap with cable ends that don’t fit. This is especially fact on accelerator cables.