I smoke Argentiine Criollo twist which has a reputation for being high in nicotine. Although strong in flavour I can't say I've noticed it as being any different nicotine wise from the likes of SG Irish twist. Then again I do tend to take my time when smoking 'strong' blends. To be honest I'm not sure if I know what the diffrence is between a strong blend and one that's high in nicotine.
I guess I'd say that Mixture 79 is a blend that's strong in flavor and weak in nicotine.. maybe the same for Captain Black. There are other examples. My tastebuds are pretty basic though, I can only tell if the smoke taste "good" or "bad". I get ahold of some blends though that cause a little buzz with maybe even a green feeling if I haven't had a meal recently. I'd say the SG ropes have this quality.