Re: Ingersol-rand 27hp
Your title says it had a 27 hp, go with something close to that. An aircooled engine would be a far better bet. Lighter, more compact and easier to hook up plus parts are readily available. The belt drive will allow you to run the engine and pump at the speeds they are designed for, large direct drive compressors do exist but are designed as a unit for specific applications. Keep it simple.