I have those early headers on my car and they do sound better than cast iron manifolds and I think they give more mid range torque.
The throttle linkage ls different and you will need to get a flat metal side cover plate instead on the aluminium one with a pin. There is a small bracket that goes on the plate and two threaded screws that you can make in your shop. The rod coming from the firewall is also a different length but you should be able to make it longer or shorter as required. The hard part will be finding the bracket that goes on the side cover plate.
The early 230SL engine produces more HP per liter of displacement than a 250 or 280SL. This is probably done through cam timing, distributor advance, and exhaust headers. In my opinion, early 230SL's should be as coveted as 280's.
I believe these are all of the part numbers needed aside of linkage rod size adjustments.
180 015 07 05 cylinder side cover qty 1
180 015 08 21 Gasket qty 1
180 072 01 81 Threaded Pin qty 2
127 070 24 40 Support Bracket qty 1
127 070 16 22 Lever qty 1
006799 007001 clip qty 1
000934 006006 nut qty 2
Doctor Benz. I cannot agree with you more on the collectability of the 230SL model.