I put up a suspension setting for the 66 AC cobra 427. it can't be that off from the american version.
however, I have updated the suspension a little on it. with the settings as they were when posted my best nurburg time was 8 minutes, I have it down to 7:28 and some change with the new settings.
the problem with the car is it is extremely light, with any bump it will get squirly, especially if you are braking and go over the bump unevenly. I haven't been able to tune that out without totally trashing the handling of the car. and seeing as there are only 3 places on the ring where that really affects you, it is something I have decided to adjust to with my driving.
anyway, when I get home tonight I'll post up my new settings in this thread. maybe they'll help, maybe they'll at least give you some ideas (this is afterall my first car to seriously try and tune the suspension on).