Good topic. My 2 cents. I am sure those more knowledgable than I will have some great information. I used to chew for many years and there are times I crave the nicotine. This has tappered over the years. With pipe smoking for me  its not so much about the just nicotine but the whole experience: the flavor, the ritual, the relaxation, the cerebral stimulation and yes, a bit of nicotine. I have never got the nicotine level I experienced when I was chewing or when I would have the occational cigarette. Its hard to do with pipes as you dont generally inhale the smoke. What I have found is that if I smoke for a long time, 30 minutes to an hour, the nicotine slowly and gently comes on board. If I am in desperate need of nicotine, I reach for a pouch, gum or the like. If I am ok with a more gradual nicotine fix, i prepare for a longer smoke and I will go for Peterson Irish Whiskey or Cornell and Diehl Old Joe Krantz original ( brown can I believe). General rule, latakia and cavendish are very low. Virginia and Perique are a bit higher. Happy hunting! I cant wait to see the other suggestions!

When I picked a pipe back up almost 25 years ago, I had been smoking cigs and cigars, so I had the same desire for strong tobacco as you describe.

Highest nicotine tobacco available (from strongest to weakest) is Gawith Hoggarth Dark Plug, Dark Flake, both the Aromatic and unscented, Brown Bogie, Brown Irish X and the variations of it, Whiskey Twist, Rum Twist, etc. Following closely behind those is Mac Baren Rustica. Lesser, but still quite strong would be Mac Baren HH Old Dark Fired and Bold Kentucky, C&D Old Joe Krantz and Billy Budd if you want a strong Latakia blend, then following down would be Peterson’s Irish Flake and 3 P’s. There are others but they are a little more obscure. 

Ted mentioned C&D's Billy Budd. I would think some of the other blends with cigar tobacco in them would have higher nicotine content also.

Warhorse.

I was in the same boat as you smoked cigs and switched to the pipe 20 years ago. I smoked Marlboro reds. Those above recommendations are good, but you can't smoke ropes all day long. You can try what I do and Try Virginas which are readily available if you want to inhale go right ahead! for daily nicotine and not heavily topped with artificial flavors. What i cellar and smoke daily and these are staples if you want to replace cigarettes. probably a good start.

Virginia 

gl pease Union Square  

Peterson flake 

capstan blue 

G@H Brown flake if you like a dose of burley

Virginia perique 

Elizabethan Mixture