Fireplaces and furnaces

Last week in addition to the 3 doctors appointment I had, I also had multiple walk thrus with contractors to provide estimates for the furnace conversion (oil to natural gas) and exterior siding/millwork repairs and paint. We have narrowed down our appliances and are almost ready to pull the trigger on this. Good thing too, because the temperatures are dropping.
The old furnace we have been told is probably the original coal burning fireplace which was converted to oil at some point. We received our first estimate in May. The consensus is that we will need two few furnaces to replace it based upon our heat load. We are hoping to maximize our tax credits by getting the most efficient furnace. I originally tried doing Energy Trust of Oregon, but that is in part sponsored by the gas industry so switching from oil doesn't apply. I was instead referred to Clean Energy Works Oregon. We would need to have at least a 95% efficient furnace so that is what we are looking to achieve. The natural gas company will not charge for the connection to the main line if you convert both a furnace and a water heater. We also want to run a gas line to the dryer (we brought our energy star appliances from our bungalow), to the stove (Mr. W hates cooking on electric), and to the fireplace. I still have a lot of work on nailing down the incentives, credits and rebates, but I think we are pretty much ready to go once we recieve our second HVAC bid.
One thing that needs to be completed first is repairing the firebox before we have a gas log setup installed.  Being a 120 yr old house one can imagine that the masonry is in pretty rough shape. The mantle is very nice though, I am pretty sure it is marbleized slate. The veining is not on any of the edges or the underside of the shelf. From what I can find marbleized slate was a popular fauxing treatment in the late 1800s. It also has some nice incizing across the top and flanking sides.
 
The interior is not so great though. The deteriorating masonry of the firebox was among many issues that came up on our home inspection. 
 
There is an old log basket, I have no idea if it would be original or not, but it is nice enough looking that I want to see if the gas log supplier can incorporate this into the set up rather than using something new. (Also not sure why there appears to be two stacked on top of each other.)

 I also think that this row of tiles was added at some point since it is only at the top and not the sides; I would think it would have been more balanced if they were original. If possible I would like to have this removed. I have been researching salvaged firescreens and summer covers on line and during our vacation to DC earlier this year, and the dimensions of those heights seem more in keeping with that of the marble, not this row of tiles.
 
  Here are a couple salvage pieces at an online salvage shop in Chicago. I would hope to find something closer to home that matches my dimensions. I can't image how much shipping would cost. Getting this is a long term goal, as is replacing the tile o the hearth.  Our budget can only handle so much right now. (Shakes fist at infertility!)

 

 Lastly the hearth seems to have been replaced with modern 4x4 tiles at some point. But my guess is it was a DIY job and they didn't prep the substrate properly because there is a giant settling crack in the center of the hearth.

The winter issue of Old House interiors coincidentally has an article of fireplaces. (Well maybe not so coincidentally since lots of people are probably thinking about warming by the fire this time of year.) Anyway they had several sources for Victorian style tiles: L'Esperance and Derby. I can already tell I'm going to have too much fun with this (not to mention disappointment that there is only one fireplace in the house!)