Hi
Go for a 1986 - 1989 model ( facelift model)
All sorts of improvements and loads of threads on it ( try searching facelift SL in this forum)
Yes there IS a 300SL available BUT it's a Euro model - there are some about in the US and "I" think they are great
(I've got one here in the UK) but they tend to fetch a premium in the US.
The most common US model seems to be the 560SL.
Cheers
Jim