I would not hang a tv above the fireplace without protecting it with a mantle of some kind. The tile directly above my fireplace for at least 2 feet gets hot enough to burn your hand.

The only way to now for sure if the logs are ventless or vented is to find the make and model and look it up.

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Ventless and gas are 2 words I don't think go together... Considering some states have banned them, I would do a lot of research on the safety issues before proceeding. More on reddit.com

I retired from that industry after 25 years. I never understood why people chose to put a fireplace right below a very expensive piece of electronics, which do not like heat, over top of a heat source. And you have vent-free. 100% of the exhaust that the fireplace makes goes right up the front of the wall, and the second thing it hits is the tv after heating up the wall good. If you read your owners manual, it will tell you exactly where you can place a mantle shelf. Remember, it too is going to get very hot, so I would recommend a metal heat deflector on the bottom side of it. It is not going to solve the problem, however. The wall will continue to be extremely warm, and the tv is going to get too hot for its own good. Heat rises, you can't stop it, only try to redirect it. More on reddit.com

CO shouldn't be a concern. The unit itself will have a shutoff long before O2 levels get notably depleted. If your house is too airtight, then it might kick in frequently. Otherwise it never will (and with a 1960 house, it's probably plenty non-airtight unless someone's done some major eco-renovation on it). The two main concerns are humidity and the slight combustion remnants that some people claim they can sense and affect them adversely. Sounds like humidity isn't a huge concern for you, though if you use this thing a lot it will dump a lot of moisture into your air. IMO, if you want a fireplace for a "every once in a while" type thing, then ventless is fine. If you're going to be using it every day in the winter, pony up for the direct vent. I've actually purchased two used direct-vent fireplaces, so consider that option. Though venting materials alone will add ~$300 to the package unless you have an easy out-the-back-wall option. (Sounds like you'll be going up the existing chimney, which is another good option, but requires a healthy amount of stainless ducting.) More on reddit.com