Why not do the heater upgrade?
Use the motor & cage from a 78 1/2 ton chevy pickup. Carquest part number #208971 (motor) & #209109 (cage). It is about a 30 min upgrade. You will need to cut the opening in the heater box larger. (I used a dremel tool). Use the cage as a guide. Then secure with some self tapping screws. The results are amazing. Cost under $40...
Carquest # Napa #
208971 455-1039
209109 655-1406
Napa blower motor # 455-1039 = Advance Auto p/n: 35587 for $20
Napa squirrel cage # 655-1406 = Advance Auto p/n: 35602 for $14