A few of mine include a V8 Mazda RX8 which isn't super crazy surprisingly enough and a mid-engined classic VW Beetle (Best options from what I've thought about is a transverse mount such as a Honda motor or a Chevy LS4 where you pull the entire front subframe from a car, drivetrain, suspension, and all and proceed to fabricate mounts for it in the rear end of a Beetle. Other options include transaxle longitudinal setups).
If we’re not trying to be completely plausible, I enjoy the idea of swapping aero engines into cars. Take the Napier Sabre engine, for example. It’s a 24-cylinder H-pattern engine that was used in the Hawker Typhoon and Tempest aircraft (among others) during World War II. I believe it initially produced 1800 horsepower, but later versions hit 3000 regularly and the last experimental model broke 5500. Sure, you need to put this in an aircraft hitting 400 kph or higher just to keep it cool, but in a serious drag car? Damn, I just want to see what would happen.
Interesting idea, it would be interesting if something like that showed up at a drag strip. An advantage with that is that you wouldn't have to worry about wheelies, those motors weigh so much XD. Got any plausible ideas?