Quick sit rep; picked it up to day and it's probably better than it looked in the listing. Apart from a few bearings, what is there should clean up into a useable state. What isn't there is mag, carb and inlet pipes, idler gear, oil pump and miscellaneous fasteners. EDIT; Also one valve with guide, spring etc and a tappet cover.
Still don't think it's one I want to do but at least it's safe.
Cylinder dims confirmed as 88 x 88mm as per pre-war light car BTW.