I would carefully draw out the room and take some actual measurements with a tape measure and put them on paper so you know how far your seating distance is, how big the room is, and how much mounting distance you may have to work with. I have a pretty normal two-car garage, and that thing is about 20x20, which is also an 'OK size', but actually a bit smaller than I'd like. So, I'm not sure how you end up seated 6-8 feet in a typical garage sized space.
Average screen size for most home theater enthusiasts is 10" to 12" of screen diagonal for each foot of viewing distance. So, at 8', having a good quality Samsung with a 85" screen will deliver nearly unbeatable quality compared to a projector. Projectors just can't do HDR justice, so you lose something. If your viewing is more like 10' away, then a 120" screen would be far more appropriate and would really give an immersive setup. But, I would struggle if viewing from 8' away to get a 100" screen over a 85" flat panel in most rooms. But, that's my take.