Should be. Commonly referred to as a "pony motor".
FWIW, Do your son a favor and tell him to keep looking for a grader until he finds a CAT. CAT parts ain't cheap, but they are a helluva lot cheaper than parts for orphans. An old wrist breaking #12 shouldn't be terribly spendy, and will be a lot cheaper to own/run than about anything else.
Years ago my Dad bought a WABCO 777B with an 871 Detroit in it. He gave $25K for it, and that thing was big and would move the hell out of the dirt or snow. However, it never finished a job that it started. My best guess is he dumped another $75K into it and STILL it never finished a job it started. And it wasn't just the Detroit part, although it got overhauled, too. Transmisssion, finals, hydraulics. I think the W in WABCO stood for WEAK instead of Westinghouse. He bought an old #12 for not much and it was the Energizer Bunny, going and going and going. We unloaded the 777 at a heavy equipment auction and never even watched it sell. When the check came, it was for $5400. :shock: Dad was tickled to get anything for it.