Hi Serg,
I own a 230 SL 1963. The early 230 SLs are more bare (interior) than the later 280 SLs. I prefer the earlier 230 SLs. The 250 SLs are rear in that they were a very few produced compared to the 230s and the 280s. My car is manual but I always wanted an automatic. However I have come to love my manual and I did test drive an automatic, but prefered my manual. This is a matter of personal preference.
As for parts be it the interior or exterior, they are all available from different sources including MB itself. There is a good parts supplier in europe by the name of sls. When you visit this site, on the main page there is a link called "links". When u click on this u will be navigated to a page with a myriad of suppliers.
Ok here is a tip from personal expreience. Restoring these cars can be very very expensive and time consuming. Please try and purchase a vehicle that has minimal or no rust. A car that runs and has known problems which can be easily fixed. And one that requires not much more than a fresh paint job. If a car in this condition runs you about $15 -20K, get it. Do not buy something crappy for $8-12K. The amaount of money u save in the initial purchase of a crappy car, you will pay atleast 4 times that amount to get this car into a decent shape. Also there maybe some members here who are selling their cars. From what I have seen on the site, they are enthusisats and a lot of stuff about their cars is documented on this site and they have been caring and kind to their machines, so you could pick up a relatively reliable and cleaner car from this site. But then thats just my humble view from what little I have observed. Happy Pagoda Hunting and good luck.
Hope this helps,
Regards,
Hassan