prop test engine- cheap

What have folks found to be the cheapest engine to swing a prop for
function and reliability testing? Needs about 100 hp at 2500rpm with
maybe a little extra up to 2800rpm. I would rather not go direct drive
if I can help it but that might be the cheapest way.

I thought about jacking my truck up and using a shaft off of the
driveline in some sort of big steel fixture. Now that would be
interesting. Heck, I could make a barge for my truck and "drive" it
around the lake like a big airboat

Seriously though, what's the cheapest option out there?

Joa