Military ground power units should already be hardened against EMP affects. The engine I am thinking of was a Lycoming air cooled design. It was almost the same as the engines used in some small aircraft except it was not certified as airworthy.
"I've loaned it out to dairy farmers when their barn ventilation fans go down. The cows look like they're behind prop wash from C-130's. Tails straight out from the velocity and volume. LOL!
The airforce used to run a lot of those Cesna centerline thrust pusher/pullers. That was one noisy bird to be inside! The mechanics never worked on the Lycomings, they just replaced em. I think they were Six Cylinder 400 CID engines. Somewhere around 300 HP per engine. The engine swapping phenom produced a lot of "serviceable but not airworthy" engines during the 70's. They used em on airboats, television sets for creating high winds, and as you said, many other uses. Today a run-out engine core fetches $6,000 to $10,000 a copy. How times change!