ship it to LB!

I just went through this on my 3.6L, maybe a little worse looking. The #3 cylinder hex nut had rusted into a pile that no longer resembled anything and the inside of the barrel nut was rounded. The Sears bolt/nut extractors would not fit and neither would a dremel tool with fiber cutting blade. So I heated up both nuts with MAPP + Oxygen until red, just to the point of going molten and then turned off the MAPP. It took less than 30 seconds with straight oxygen to cut each fastener basically in half. I wacked each nut with a flathead screwdriver for good measure and then sprayed them with water and eventually unscrewed by hand.

I think you can get those w/ the proper torch set up, and maybe some Vice Grips. It doesn't take much torque to turn the nuts once you've heated them properly. I've busted worse, this stuff is the norm in marine environments.

One problem (that I had) is that depending on the cylinder there is no room physically to get vise grips or anything (nut extractor, etc.) around the fastener.

I use an electric die grinder (Dremel on steroids) and a 3" fiber cutoff wheel on lost causes like that. I also agree you are a candidate for replacement studs, that's the worst I've seen in a long time.
Wear eye protection and have an extinguisher handy, you'll be throwing a lot of sparks.

Regards,

The HE's have been hacked off so now I have a clear shot. I will hit them with an Oxy/Acet torch and some more PB. Hopefully I can get some to come off. I will then go to the Dremel to slice the nuts open and save as many as I can. The heads are going to go to Comp Eng for valave work so I can have them replace the broken ones. I'm just hoping to handle some myself so I don't have to pay them $25ea.
Stay tuned.

Put the spurs to her, Chuck and don't try to finess it. Cut those bastard off. Think of it a minor demo job.