Help please to ID this plane

This photo from the collection of a late RNZAF mechanic from here in Cambridge has me wondering, what is the aircraft. Bearing in mind this looks as if it is in the Centennial Buildings at Rongotai, where he trained as a mechanic in 1940, I assume it is an instructional airframe.

My initial reaction was it’s a Harvard, due to the metal prop etc., but then I thought it might be an instructional airframe that used to be a biplane and had wings removed, a common practice in those days for training engine mechs. Or may just be an engine on its own on a testbed or something.

Does this look like a Harvard engine and prop assembly to you chaps? Or could it be something else? I’m no expert – all radials look alike to me -and I have no pictures of a Harvard with the cowls off to compare to.