If you really like your 40, look at a 41 Nash 4 door. It will surprise you with the details on the fenders, rear deck.
Another odd ball I had was a 36 Hupmobile Aero 4 door sedan. It had sucide doors on the rear and looked for all the world like a 2 door sedan. Lots of excellent details also like curved corners on the doors, flush drip rails.
How about an early 50's rambler wagon? They make good milage with a sbc yet move right out. Think "Father knows best" type of car.
A little later suggestion is a Nova wagon, 69 or so, with a complete 68 Camaro front end installed. Most of the stuff bolts on, only have to make the door lines match. Result is a Camaro Wagon...
Good luck with your search.