Broken head overhanging threads

Picked up an 84’ gpz 550 for a good deal. Bike sat for many many years. Upon diss assembly I noticed this broken off piece that secured the valve cover. 

Wondering if anyone knows a good way to repair. Is welding a piece then retapping the only way? 

I have a spare engine out of an 85’ but would like to salvage this if possible. Thanks. 

It would need welding and re-tapping if you want it to hold pressure on the gasket. I suspect anything less will result in incurable oil leaks

That’s what I’m figuring. Just wanted to see if anybody had any creative ideas.

I agree the correct way to fix that is with a weld. bore and tap as Wookie suggested. I can not tell from the pics but you might be able to build a clamp (threaded rod and nuts etc) to put some pressure on the cover/gasket. But it would only be a temp solution at best.

I appreciate your input. Time to go find someone with a TIG!