Is it worth trying one of those threaded inserts (helicoil) if I have to resort to drilling the whole things out bigger?

 

Without sounding like a Smart XXX, I would suggest lefty loosey, and Righty Tightey!

The dremel tool is what I have used to get rid of those EZ outs out. Have never used them in years as I have a set of Rigid stud removal tools. Centers on the bolt so the hole is drilled in the middle and then drive the tool in. Also have found the left fluted drill bits to work very well. Heat is another option and that is where the welding ideas all will work.

Wishing you success on this project.

 

Thing is, that ease out is HARD HARD HARD. You'll see. You'll dull a titanium bit tryin to drill through it. Probably your best bet is to get a hammer and small punch and try to shatter the ease out. It's so hard, it shouldn't be too difficult to break. Whoever you find good enough with a TIG should be able to do all of it.

 

Those screw removers are awesome! I just ordered a set..
Thanks Toad..

 

those Grabit's are life/time savers worth every penny.