I bought my '69 280 SL (5 speed) 1+ years ago and just found this site recently once I got some time to dive into its few "issues". The site is great!
The car runs really strong, but it had a skip after about 4000 RPMs. Ran great up to that, so really not a real drivability problem, just very annoying. The idle was a little high also maybe 1300 RPM. I tried all the obvious tune up stuff with ignition parts, wires and new fuel filter etc. with no result. The PO was told he needed an Injector Pump rebuild (I hoped not).
Read various threads and read about the critical linkage adjustments and the "Linkage Tour". Sprung for the full membership and downloaded the info. THE best money I have ever spent. I made the initial adjustment to the throttle ventuti screw and adjusted the rod. (Have not even done the full linkage adjustment yet). Test drive and WOW, it pulls to (and beyond) 6 grand now with NO SKIP. Who knew that linkage was so critical! Idle is now 1000 warm, which I like fine, though I know some fine tuning may be necessary after the venturi adjustment.
Full membership is the "bomb"