Ok. Well easy way then to check. Get onto the highway, let it go into overdrive and see what your rpm is at 70mph. You have a 27" tall tire
with 4.10 = 2642
with 3.73 = 2239
with 3.55 = 2131
4.10... 4th gear at 40mph will put you at 2324 rpm
3.73... Same gear at same rpm puts you at 2114
That calculator you used they base the 4th gear off a 1:1, which yours is a 1.14, a 1.00 is a true 1:1, so that won't be too accurate.
This is the one i use, and its been dead accurate for me, it doesn't give you the axle ratio, so you have to work in reverse order kind of, but its easy to just plug in numbers to see where it should be.
So it actually sounds like you have 3.73s based off of the rpms you were at in 4th when you tested.