One of my Model T friends built a T with 2 engines but made it a straight 8. It is now in the Speedway museum in Lincoln NB. A V8 would be a real challenge.
Decades ago, my father worked with a guy who made a V8 engine out of 2 Peugeot $)$ engines. French engineers from Peugeot came to see what he had done. Last seen, they were still scratching their heads!
Originally, the 404 engine was a slant 4, so loaned itself to being reborn as a V8.
The original Pontiac Tempest from '60 to '63 had the right half of a 389 engine. The distributor was in the correct place at the rear of the engine and used a 8 cylinder distributor with 4 of the holes plugged with rubber stoppers. It was similar to the picture above. The transmission of the vehicle was in the rear and had a flexible drive shaft supported with four bearings.