Our house was built in the 1970s and we had a similar dilemma. We covered the brick added a new mantle added black granite tiles as well as covering the opening with a cover we bought at a home improvement store. We also widened the area a little as well to offset the mantel. With the doors shut it looks very modern and clean and hides the internals.
Hopefully this gives you some ideas.
BEFORE
![enter image description here][2]
AFTER [2]: https://i.sstatic.net/9t0hT.jpg