I would attach a model airplane internal combustion engine to a gear box
and the gear shaft to a long threaded rod with a matching nut soldered at the end
of a copper plumbing pipe with a slightly larger internal diameter to fit over the threaded rod.
Reverse would be a problem, unless the gear box had an electro-mechanical gear swap for reverse.
On the other, a long piston, slow, Stirling engine could do push-pull. That is not internal combustion.
It is external.
Maybe the egg suction technique could be used: That is internal combustion.