The Mega Buck Pantera has a twin turbo SOHC Cammer. Last I heard it's in a private collection on the eastern seaboard. I forget what Shelby American it's in. The engine compartment was the back cover.
Nobody knows if the J Car broke up before or during the crash - only that the epoxy connections failed. The MKIV also had a steel roll cage added to it.
The YF12 was basically an armed 2 seat SR71. They still fly a SR71 modified with 2 seats (it was the trainer for pilots with an instructor) at Edwards as a chase plane for really fast experimental stuff. A guy I know had them fly a wing section he designed on it to watch the air flow. They have a pylon on the plane and mount a scale section of the wing to it. It's painted with some magic paint that changes color as the pressure on it changes. They film it at speed and watch the pressure wave flow along it. The A 12 was the prototype of the design and had an aluminum skin. The extreme heat that the friction of the air caused ruined the temper in the aluminum skin. They went to a titanium skin because it would take the heat. All the parts for those planes were tracked at each step by Lockheed. One of the forgings was cracking. They found the ones that cracked had been machined during the summer and traced it to the fact that Burbank water had more chlorine in it during the summer. They started using distilled water for their cutting tool coolant. There is an A12 and SR71 at Blackbird Park in Palmdale CA. The sole remaining YF12 is at Wright-Patterson.
https://www.google.com/maps/search/spy+plane+park+palmdale+ca/@34.6030021,-118.08684,177m/data=!3m1!1e3?hl=en BTW: The B2 was built in the Ford Pico Rivera, CA assembly plant. Northrop bought the place from Ford and built all the parts there then trucked the pieces to Palmdale for assembly. Today it's a shopping center.
Billet will never have the pound per pound strength of a forging. When you forge something you force the grain structure into alignment. When you cut something out of a block you end up cutting through the grain structure and building in weak points. Casting a part will help the grain structure align but still isn't as strong/dense as a forged part.