I reread Gus's reply (DADS50) to my questions about my heater. If your 6v blower motor works, then I agree with what he said ...
If my original 6v was still good I would have just used it with a voltage reducer.
Original 6v delco motor will be superior than any replacemet motor. IMHO
As Woogeroo noted - check your heater core for leaks and flow. Also check the Ranco valve that controls the heat. They are available rebuilt - not cheap. Or, search Stovebolt for instructions on rebuilding. Reproduction heat control rod and brackets for the rod and air control are available from a few parts suppliers. New defroster hose - cloth or plastic - is available from parts suppliers. Some heaters use 2"diam and some use 1-3/4"diam. Reproduction defroster vents are available from the suppliers. "Real" ones are sometimes on ebay or available from other Stovebolters.
Here are pics and details by Brad Allen.The '54 windshield garnish strip has stand-off clips under it that allow the defroster air to blow onto the windshield. Check to see if they are still there.
Here are pics of them by Tim Lederman.Here are pics of the stand-off clips that I made.This is the full post about the clips.