Is that 100" diagonal or 100" width for 2.35 aspect ratio? If 100" screen width, then it will translate to 66.67" screen width for 16:9 and 75" diagonal. In any case, your 16:9 screen would be very small, almost can be called tiny. 4:3 aspect ratio would be even more small. If I were you, I would go with 16:9 aspect ratio that size and may be mask it down to 2.35. Constant Image width and no zoom.