The steering wheel will physically fit, no problems..
However the Omega steering wheel controls are physically bigger than the steering wheel controls from other models. (Just like you said basically).
You can take out the boards for the steering wheel controls, however you will still have the problem of obtaining the switch trim bits to fit these to.
The other alternative is to carefully cut the switch trims down a bit to fit the leather trims.
Or alternatively, you can source new/used steering wheel switches.
FYI, the only difference between Series I and Series II Steering wheels and trim bits is the Airbag Wiring connectors are different for Series I and Series II Models.
(I.E you cannot fit a Series II airbag to a Series I, and vice versa, without changing the connectors, or the clockspring)..
Hope this helps