Here are the pages you need from realoem.
Front suspension:
https://www.realoem.com/bmw/enUS/sho...diagId=31_0648
Rear suspension:
https://www.realoem.com/bmw/enUS/sho...diagId=33_1143
All you probably need are shocks, springs, and bump stops. Can try to buy springs from a junkyard or dismantler with a crashed 3.0si (unless the rear springs have the same cracking issue as the Z4M then might want to go with new).
It's very likely that whatever is on your car retained the stock front top hat and stock rear shock mount. Probably uses stock spring pads in the rear too. Might be a good idea to replace some of those parts anyway because they're cheap and fresh ones will increase ride comfort. Go with Lemforder instead of BMW OEM on any parts you can. Lots of options for upgraded rear shock mounts like Bimmerworld (OEM design fails quickly). Would be best to jack up the car and take the wheel off to check what's still OEM and what's in good shape before ordering parts.
Rather than OEM dampers you can get Bilsteins for the 3.0si. There's a very reasonable B4 set that's close to OEM with the part num 22-164568KT. If you want an upgrade to a slightly sportier and better damper can get the B6 but those are quite a bit more expensive. May be worth it for a 3.0si though. I would not recommend the B8 or lowering springs because ride quality and comfort are major priorities for you.