Hey, I have that same vintage air heating unit, I never installed it yet...let me know how it works out for ya, and how you mounted it and ran your heater hoses to it.
I ACTUALLY INSTALLED ONE PRIOR TO THIS ONE IN MY BROTHERS 54 CHEVY PICK-UP.
OOPS! I BUMPED THE ALL CAPS!
That's better. Anyways, the system works AWESOME! Never a problem. It is a duel mode one.
Has floor heat and defrost., on my brothers we added A/C. we ran the hosed under the fender up high so they won't bee seen. Then drilled two hones and put grommets in them then ran the hoses out and strait into the water pump and water neck. Very clean. If I remember, it only took two hours to install it all from start to finish. Not including charging his A/C of course. I may end up routing the water hoses the same way. BONUS!! they won't be in the engine compartment and that means I can procastinate a bit longer on the install. Yahh! L.O.L!