You can break it in, in the cold.
The problem is, you may need a new Piston and Sleeve for the summer.
http://www3.towerhobbies.com/cgi-bin...&I=LXMHT6&P=ML
In this cold, it may not get hot enough and will not expand as much as it will in the summer.
Then when the summer comes around, the engine expands further and you have less compression. As if the engine is worn.
You have a long winter, you can drive it and enjoy it, then replace the P/S for the summer.
Then you can have a winter and summer, piston and sleeve sets.
Wrap the head in tin foil. That will help it retain heat better. Enjoy!