-really need some help here, and, yes, i've checked through old threads first:

same old story: broken rocker stud , very few threads left to pull on, stud 'shoulders-out' quick (larger than thread dia).
assumption that it is pressed in.

looked in an old GMC pick-up shop manual and they display a special tool for pulling which relies on grinding a notch in the side of the stud, but i've been unable to find such an animal.

MIG Welder is out of state w/friend
have acetylene torches though, but dont want to fry any of the valvetrain seals.

Need help, this is the only think keeping me back from running my '56 this summer and maybe getting it sold.

(yes it's a 389, it was swapped in)

Assuming this motor is still in the car. Your easiest(?) way to fix this is to cover the surrounding area with shop rags and cut the stud off flush with an abrasive saw. Then center punch and drill out the remaining stud material. Pioneer products (available at auto parts or machine shop) markets several screw in replacement studs. Tap the hole to the correct thread and install the replacement stud.

Buy a cheap thread die the correct size and find a cheap deep well socket it will fit into, get someone to weld the die to the socket, that would allow you to get in there with the die to cut more threads then you could use a couple of pivot balls and the rocker nut to pull it out. I'd say if this is something that's happened before and you aren't going to upgrade your studs such an item would be a wise investment. We do it at work all the time and they actually last through enough uses to make it economically feasible.

so are you saying that the socket would act like the bushing/spacer in a stud type puller and the die would act like the nut pulling it out? maybe some ascii diagrams would help.
the tool in the shop manual I refered to had a threaded body that fit over the stud then a bushing that went around that, and a nut to compress/pull on the stud. well actually, the treaded body had an allen set screw that went perpendicular through it and then went into a notch that one would have grinded on the stud itself. BUT if I could get some more thread on there like you just sugested then I think I see where you are going.
but that would depend on if I understood right or not.
------|------ die?
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[ | ] socket
[ | ]
[ | ]
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stud

stupid interface deleted my spaces

I think you got it, extend the threads on the stud to what length they were originally with the die/socket contraption, then slip a couple of pivot balls or a shallow socket over the stud so at least part of the threads are still showing and install a nut, slowly tighten the nut against the balls or socket, that will pull the stud out of the head and it's fairly cheap. That's how I learned to do it back in the dark ages anyhow.