WOW you got a gem there, That engine is quite old if it's OS, I've seen pics but never seen one with the rear lifters on a OS, I think they changed them because too many people getting wacked with the prop with the glow plug pointing forward. (might be worth something to a collector) As for the plane it looks somewhat familiar but can't say for sure if it was a kit or not. (might be thinking of another kit) None the less that is a great find. actually the closest I could find was a Ace 4-120 Bipe Not sure what sizes they made but it does look alot like it just larger but you may have one of the smaller ones there

Dauntae