if you hadn't ground it all out I might try the drill and install little tapered pins. just stitch it. That's how we repaired cylinder heads.
If you have a large enough torch (rosebud) and can get it hot enough to flow brass. Braze it.
if you insist on "TRYING" some nickel rod on the arc welder I am sure you will recieve more than enough "pointers"
And if you find you just burned the hole bigger that ever.
replace the part