Thanks Kona, appreciate the advice! I think I'll be taking it to Addiction Motorsports. Eddie Rios is the tuner and shop owner. Have heard very good things from many people about him including OTHER TUNERS. He works pretty much exclusively on Mustangs and does a lot of Shelby's. That said, I'm not having him tune it. I'll probably have him read my car her last rites and confirm what I already suspect.I'm just on the sideline observing.
I wouldn't let just "any shop" diagnose it.
Trailer it if need be, AED or GTR. Those are the only 2 that I know of in California that know the Mustang/Shelby platform
If it were me, I would do whatever it took to bring it back to life.
No matter the time frame. Years if need be.
These are very good folks nearby to me. They get stuff all the time. Maybe a used factory 5.8 if that's what is determined to get it up and running again
The Parts Farm