Thank you for the advice everyone. It seems like the best course is to the split the cases and have it repaired.
The other case half I have is in great shape. Would there be any downside to just swapping the one case half? Wonder if the machining would match well enough or if the surfaces would have to be machined to match.
Thanks,
Angus
It is a casting so it can be built up with welding rods
If you are sure you want to do the full removal / replace bit.
Cut the bad bit out with the cases assembled
Make up a backing plate from steel at least 1/16" thick
Clamp it behind the spot where you want to build up
Build up a new corner, remove the steel backing plate ( molten aluminium will not stick to steel ) .
Machine /file the cases flat
drill new hole
tap hole
flush out cases
This is not a load bearing stud and is only there to clamp the sump plate yight enough to stop the oil leaking.
I hink a few here have lost sight of that.
Alternative method is to drill & tap a hole in some aluminium square or hexagional bar stock
Remove the bad repair and tack the new piece in place then do full welds both sides .