Majestic/cone shape vintage 1970s fireplace questions

[Mrothchild]

We are remodeling our house and have purchased a vintage cone shape Majestic fireplace that was originally wood-burning. We do not want to go through the ceiling or vent out and want to use a ventless log set for this. We have the dummy chimney that we would like to run and are thinking that if we Seal off the flue We can stop the heat from rising and we’re trying to figure out if this is safe or not. Has anyone done anything like this or do you have any advice on how to make this originally woodburning into a ventless?