Ok, so I have some details on what works, which I've added below should anyone else want to go down this route...

For a Sports MOMO type Steering Wheel - Use these BOSS Kits..... MOMO 6008 or 6008R. Should bolt straight on, does not require any modification.
These might be advertised to fit Mercedes w202s / w210s and w220s but works on the Mercedes R170 and CROSSFIRE as well.

Further option, to retain a Mercedes aftermarket style steering wheel, with airbag...
(adapter type 160 for w202 / w210 / w220).

Atiwe Part: #170160
Atiwe Boss: #160160
FVD Part: #70160.