Gas Fireplace problem

[Sunbeam lodge]

I have a vermont Castings wood stove with an 8 inch flue opening.(overall 10 inch metalbesto pipe). I want to convert to a gas fireplace but have no way of direct venting thru walls or ceilings. I can only use the pipe in place. I prefer to go to a direct vent system if possible but may have to consider a B vent sytem.
Gas stores say it cant be done. Any suggestions anybody?