I have mounted my 75" TV on my 6.5 feet wall. No problems with mounting. The actual mounting is done on a 1 foot or so square bracket. My viewing distance can be anywhere from 6 feet to 10 feet, depending on what I am doing.
The speakers are a problem though. I have my speakers on stands and for watching movies, I have currently placed my speakers on it's side !!!! Not much impact on audio that my old deaf ears can discern.
I would suggest that you plan for a 75" TV and carefully plan your TV placement and your speaker placement. It is possible to do it in a 6 feet space with sufficiently good results.
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