That would be 108kbtu, but you are likely oversized. With proper duct configuration including ACCA Manual D calcs and air sealing, you will most likely be more than fine with 96kbtu. Most systems (even in very nice houses) are just sort of thrown in rather than actually calculated, and then they are installed sloppily with a lot of leakage and only roughly resembling the design in at least a few locations. I do these calculations for a living, and would recommend presuming that will be the case until proven otherwise. Obviously get hard numbers before full commitment.