I think a Sherline would be the best way to go. LOTS of tooling and accessories available from the factory plus aftermarket support as well. It's a great value for American-made machinery: I don't know of any websites dedicated to getting rid of slop in a Sherline, unlike some Asian tools. Check Craigslist as well. You can get a free cell phone app called Craigslist Pro and have several cities programmed in to make searching faster.
The Hasegawa kit was originally issued about 10 years ago. Unless they made an all-new tool, you can find them online now. Read Alex Kustov's review/buildup here: http://italianhorses.net/gallery/hasegawa/hasmiura/miura.htm
The inline-6 in Tamiya's Jaguar Mk II Saloon looks very nice. The race version has Weber carbs. Roden offers a model of a 1/32 Mercedes engine as used in the Albatross D. III. Add Webers and custom headers and that would make a heck of a show rod engine. <ahem> if it's the right size.
If you go through with this and want to have molds made, choose someone who does this sort of thing for a living. Someone whose work you can see beforehand. I was involved with getting several people to purchase the masters for a 1/8 scale Barracuda. It got passed around to several guys who couldn't make anything happen and now has apparently vanished. You may get a case of sticker shock, but that would be nothing compared to your expensive masters disappearing. The model will be expensive. No way around that...unless you are fabulously wealthy and plan to lose money on this idea. I have to say, I think a 2 door would be a better seller. I know that's not what's on the show, But coupes just sell better. They also get customized and restored more. I have never seen Supernatural. I don't know the first thing about it. I also have no idea what you would charge for the model, but I will say that I would spend $500 on a 1/6 scale 2 door. Maybe more.
That "Snark" missile on the bottom makes a cool start for a World Absolute Land Speed Record car (thrust powered). Just use the airframe. Turn it upside down, so the bottom will be flat. Fill in the holes where the wings mount. Add wheels and a cockpit and you have something like the Blue Flame or Budweiser King rocket car. You could graft on side intakes from something like an F-80 or F-104 to get a jet car. Maybe even use the Snark air intake above the canopy, like the new Bloodhound LSR.
I don't have a list ready to go, but I just bought a copy of The Guns of Navarone, mainly to see Gregory Peck. I'm going to pick up To Kill a Mockingbird and maybe even Roman Holiday to see more Gregory. I also have a copy of Spartacus. I think Laurence Olivier is brilliant in it. Just a great flick all around, but wow, he did a great job as Crassus. Also a big fan of Vincent D'Onofrio. I'll go see The Magnificent Seven. I watched one of the Men In Black movies with him in it, at home. Mom came over and I pointed him out. She thought I was joking. She looked it up online to be sure.
I think this project is intriguing, so I did a little research. There's a 1/32 B-25 made by HK. It has R-2600s. They are twin row 14cyl engines, but the way the kit is made, it wouldn't be a huge problem to make a single row 7cyl. Expensive kit, but maybe someone at Aircraft Resource Center or Large Scale Planes would part with one engine. If that doesn't work out, Williams Brothers made/make several 1930s racing planes with an R-1340; a single row 9cyl engine. If you can live with 9 cylinders, that may be the way to go. Those kits are cheap enough to buy just for the engine. They include the Gee Bee planes, Laird Super Solution, and Hall's Bulldog.
I've got a pair of resin R-2800s somewhere around here. Will trade for a kit. I'm into street rods, lead sleds, and pre-war coachbuilt classics...but I have pretty much every pre-war luxury car ever made into a kit. Would love to have a '26/'27 T Coupe (if one is available) or an AMT '32 Chevy roadster. The R-2800 is a twin row radial, btw. Engine from the F4U Corsair and P-61 Black Widow, among others.