Just curious, why do you have the Koker in your garage instead of your basement? I know you stated you have a newly built chimney, so I'm guessing you built it next to your garage.
You might want to consider putting the Koker in the center of the basement right under your main ducts, connect the heat and return directly to the Koker and use a power vent thru the block wall for venting. (I'm again assuming you don't have a chimney in the basement).
Anyhow, just wanted to point out that the Koker will give you a lot more heat throughout the house when it's connected to the same ductwork your original furnace uses.