Hey Frank,
I copied pics/plans, as available, for all three versions I've found. They each are different to varying degrees: The "400", .15-.19 size, has the cockpit moved considerably forward, inverted engine with high thrust line, and has those odd little forward-rudders or winglets or whatever, added. The "1/2Arrow" uses a completely different profile which IMO gives it a somewhat awkward look, upright engine with uncowled head. I like the original (color picture) with the cowled upright engine and unbroken line encompassing cowling, cockpit and rudder--is that the plan set you have? Hope so.