One disadvantage to propane is that you'll get a strong layering effect from top to bottom in your room. This can be a good thing if one is keeping a variety of species but may not be desirable for a room that primarily holds ball pythons.
I also think propane is quite expensive in the Northeast.
If you have the capacity my first choice would be large radiant heat panels run on 220V.
My snake room is in the back of my garage in South Dakota and I use electric radiant heat at 220V for heat. Even when it's below zero outside I can heat that room for probably just a couple of cents an hour.
When you finish this room make sure you insulate the floor, especially if you plan to use radiant heat. Also be sure to use a foil faced insulation.
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Currently keeping:
6.10 Gonyosoma oxycephalum (Javan, mixed colors)
0.0.4 Rhynchophis boulengeri
1.1 Philodryas baroni
1.1 Lampropeltis triangulum multistriata
0.0.1 Rhamphiophis rubropunctatus
0.0.2 Morelia viridis (Aru & Merauke locale types)
1.0 Rhodesian Ridgeback