Welding the rear bumper of a P5b

The rear bumper on my P5B was pretty grim,I had a badly rusted and damaged spare and I thought I'd see if it was possible to get it to a state that it could be powder coated or even sprayed to act as a spare.The rust on the ends of the bumpers had gone through,it seems to have started from behind the fittings for the bumper bolts.

Cutting the hole square after a bit of poking with a screwdriver I cut a plate to fit flush into the holes and MIG welded it in place.

After grinding and filing it down,it looked alot better but there are a few pin holes in the welds and around the edges.I might try filling these with braze.