I think your trying to talk yourself out of the extra work to put the 115 on the CV???
Do it once right, and then your done. I have a 1972 CV16 with a 1973 Chrysler 120 on it; I think that old 120 is more like that 90 your thinking of putting on the CV. My top speed is 41mph, without trim. Acceptable for what I do, but I do not pull skiers with it. For one thing, these boats are so light they pop out of the water and on plane in a snap (even with 4 people in the boat). Tubing does not take a lot of horsepower, but pulling a 200 lb skier out of the water quickly . . . you want all the horsepower you can get.
I know if my old Chrysler 120 ever decides to give up I'll be hunting for a Johnson 115; they are just good motors.
Best of luck.
David