I have 13ft from back wall to front wall i want to mount on rear wall.
Looking at the acerhb6510. Or similiar in price.
I was once told this on the forum, Should help you out a little,
The "required fl" is actually personal preference, but if you you go by the industry standards. For a dark room,the Society of Motion Picture and Television Engineers (SMPTE) is 16fl(+ or - 4fl). For 2D in a dark room, with darkened walls, this is the movie industry standard. For 3D, you lose a little over half of your brightness and so the fl needs to be measured through the glasses.
The standard: You want 16fl calibrated for a dark room for 2D and 16fl calibrated through the glasses in 3D for an equivalent 3D picture(21fl is the IMAX standard and the upper end of "bright" for a 2D picture and below 14fl is not recommended for most viewers).