Well, yer pretty much boned. Where in CA are you? There are pretty much two options here....
1) Yank out and disassemble the block, take it to an EDM shop, and have them burn it out for you. Spendy - EDM machines that will handle engine blocks are NOT cheap!
2) If you're not too far away, I've burned out bolts with a torch before. Most times, the thread is undisturbed, but there are times when a Helicoil was required. Cost is negotiable, I'm in San Jose. I would prefer the removal of the block and its being mounted on an engine stand so I can turn it around... I can do the job there, but I'll need the block where I can get easy access to it - if you can't pull the engine, I'll require that you remove the hood, and I'll need you handy while I do the job...
5-90