“Want to build a BIG model I.C. engine?. And, of course, having built the engine, you could then horrify the neighbours by building a giant model aircraft for it to power! 4” gauge railway motive power, but an outboard motor, a GT lawn mower and a motor bike would also all seem possible for the clever amongst you.
The Building the Maltese Falcon Engine - Building Instructions Drawings by Jim Shelley would be an excellent fit for engineering enthusiasts and mechanics interested in building their custom engine, specifically for classic cars and hot rods.