The fuselage does have a vague Atlas look about it, the very nose, wing position and tail fin look as an Atlas should, but the fuselage top deck and the anhedral tailplane can only be the builders own modifications. MAN and RCM&E have Atlas plans, both would give you a wing section and chord to match with what you have, and the proper outlines to mod it back, if you wished. Arrow had upright engine for RE pipe, Atlas sidewinder and muffler.
Evan, WB #12.