This would be swapping one dog clutch drive for another dog clutch drive!
There is a conversion kit that makes the cone clutch Volvo Penta SX work for your OMC drive.
You can remove all of the OMC ESA equipment also.
A good used SX will out perform a new SEI drive. It also opens up the possibility for the Duo Prop.
There is????? Who sells it? And does it cost less than the $1900 that the SEi conversion kit plus outdrive cost????
If that doesn't cost 3x as much as the SEI kit/drive combo, that would be a nice way to go. But I am guessing it's EXPENSIVE, since it's got VP involved.