Thanks for your replies. Here's additional info to answer your questions.
I wanted a Glenwood stove, but due to stove and chimney placement problems, as well as poor heat flow due to the stove having to be at one end of the house or the other, I've resigned myself to a multi-fuel furnace, which I haven't selected yet. It would be placed in the basement, have its own dedicated masonry flue, which we're discussing, and be tied into my existing oil furnace's first floor hot air ductwork. Now I'd get heat distributed evenly in every room of the first floor.
The furnace would sit directly in front of the flue. The length of the stove pipe from the back of the furnace to the thimble would be about 4 feet, and have about a 2 and 1/2 inch rise per foot. The thimble is an additional foot in depth.
I have an external chimney at the end of the house which rises 3 feet above the peak of the roof.
Recently I carefully drilled out the portion of the vertical flue that's visible thru the thimble. When you put your hand in front of the thimble you can feel the draft and faintly hear it. I then wadded up a piece of newspaper, placed it inside the thimble about 2 inches from the vertical flue and lit it. The draft sucked the flames almost horizontal into and up the flue. This was done on a day when it was about 60 degrees outside with no wind. Based on this I thought the draft was sufficient, but then began thinking that it was good because of the high heat of the burning paper, whereas the cooler stove pipe gases might not produce as good a draft.
If I had to buy my solid fuel I'd choose coal, since I understand its benefits over wood. However, since I get all my wood for free from my own property its hard to justify paying about $300 per ton for coal here in Connecticut. Still, I want to experiment with it, hence my reason for not wanting just a wood furnace.
I look forward to your replies...Gary