headbolt advice

[PoorMansPorsche]

Looking for advice from the gurus as ill probably only get a few tries on this one. half way through the headgasket change (love that theres still crosshatching at 130k)

snapped the bolt (during removal ), got the head off. drilled down and in went the extractor. PB blastered a few days ago...map gas on the workbench just in case....

heres a pic:



Ryobi extractor comes with a square head and im wondering if there might be a better one i should pick up because adjustables (which are the only thing that can fit), seem to not have enough grab and dont seem to have an exact metric (or standard) size.

any advice would be tremendous right now.
Thx,

Rob

[James 93SLC]

Got access to or know someone with a mig welder?
I'd try mig welding a nut to the top of the stud and then trying to back her out. The concentrated intense heat of the mig will help break it loose.