If I am understanding correctly, there are at least 2 ways to create this using solids.
You could create an arc in the top plane at the transition between straight wall and tapered wall and "extrude cut" up with taper and "extrude cut" down with no taper.
The other way would be to make the whole profile from the side or front views and "revolve cut" it.
If you don't understand what I've typed above, perhaps you could post your file here and I can offer a better explanation.
P.S. a third way would be to use the solid chamfer function.