[Mike Andrew]

Tough choice - weld or replace. I saw many aluminum castings weld repaired during my aero mfg. career but it takes a good shop with the correct gear including inspection equipment to verify weld integrity. It will also likely require some post weld machining to clean things up.
Once you have things on a bench you may find additional damage that precludes this option. I would make the rounds of the salvage folks - DC Auto, LA Dismantlers, Einmalig and see how much Is involved for a used replacement. This would be my choice for peace of mind.