Not sure how your theater is setup and what your seating distance is, but the 120" screen sounds pretty small. I didn't see anywhere that you mentioned seating distance. So, be aware that 10" to 12" of diagonal for each foot of viewing distance is typical.
With 25' wall to wall, it's important to draw out exactly where theater seats are.
I'm not sure how you are separating your theater space from the rest of the basement space. This is something I consider to be really important as you will want your theater ceiling to be dark/black in color, while the rest of the basement should have a white or light colored ceiling. This makes a huge difference in front projection, just as having dark walls and dark carpet in the theater is important, while having light colors in the rest of the basement helps to brighten those spaces.
I would consider that carefully before you start putting up drywall as having a basement as one huge 'space' really hurts the concept of functionality for the basement itself. Pick an area, decide what it is for, and then build around that functionality. Leaving an open basement without that separation always seems like every space is just stuffed in there instead of designed for purpose.
THIS is a storage area.
THIS is the bar area.
THIS is the gaming area.
THIS is the guest bedroom.
THIS is the theater.
All this said, keep in mind the Epson 3200 is decent, but is very much an entry level 4K model. Don't expect nearly the black levels or overall quality that (say) the Epson 5050 delivers.
I do like Silver Ticket and think they work very well as an entry level screen. But, I think your screen may be too small.
