[JWheaton]

I would add the heater/defroster without a second thought.

Where you live you will want to have the option of taking drives on brisk fall mornings. As much heat as the engine gives off you will want to add insulation to the firewall to keep that heat out for hotter summer days.

Some of the most enjoyable rides, especially where you live, are early morning ones to Lime Rock and such. When the temp is around 55 you will want the heater blowing.