Moe, have you gone through the Technical Manual? You have it in the menu bar on this webpage. You will find lots of information there on paint sourcing for both H and G coding as well as about the engines and their numbering and how to read the data card.
As for the paint - I am sure members from your area will throw in proper addresses. I had a G paint, so I ordered it straight from Glazurit. Also a Mercedes dealer mixed a tin for me to have it at hand. You may want to check - could be that your color is available at Mercedes (some of them are). If your paintwork is old and has therefore a bit different colour than a fresh one, you may need to get your car (or piece of it, but I cannot think of a piece of Pagoda to detach, glove box lid would not work as it is inside) to the paint shop who then can use scanner/computer to prepare a matching colour.
If I remember correctly early and late exhaust pipes look differently at their manifold end. If you go to
www.sls-hh-shop.de and go to exhaust picture you will see the difference and then when you look at your engine/manifold you will know which one you need.
If you are replacing exhaust pipe, you may want to look at all the gear for hanging it (search forum) - there are rubber pieces and insulation that usually need to be replaced. I would also check out heat screens - if I have them all, etc.
You may also want to explore parts suppliers other than Mercedes. SLS is one of them, but you will find a full list in the Technical Manual. Sometimes we source parts from Mercedes, sometimes not, depending on availability, pricing, originality or other features (e.g. soft top compartment seals). It is a whole knowledge -where to source what and this forum is very helpful in this respect - usually it is enough to use the Search button.
Bythe way: you will find lots of discussions on exhaust replacement...