[blucar]

Reviewing the EFV8 Restoration book I noted that the exterior handles for the 3 win cpe, roadster and conv's differ from the 5 win cpe and sedans. It could be that the main difference is that the open cars and 3 win cpe have chrome handles where-as the 5 window, etc have stainless handles.
The escutcheon, mounting, plate on the door handle is affixed to the handle, therefore the handle should not go into the door to far. Is it possible that you inserted the handle into the door on an angle, making contact with the door skin prior to the shaft engaging the inner lock set.
FYI, the square shafts on the spare 36 handles I have in my parts stash, extend 3-1/8" beyond the escutcheon.