I swapped the standard square taper double bb out of a 1987 Lemans RS (126mm rear) that I first upgraded to 8-sp drivetrain, and now have upgraded to triple.
I used an Ultegra Octalink bb, 118mm for triple, and a new triple Tiagra crankset.
The triple FD is RSX and the long cage RD is Sora, with Sora 3x8 STI's.
Everything went on well, and easily, the RD is smooth. The bike rides well and shifts effortlessly on the small ring and middle ring. No matter what I set it at, I can't get the reach for the big ring.
I've got a lot more room between the chain stays and the chain rings than on any of my other bikes.
It seems like a step down to a double Octalink may do the trick. How about it?
I'm using self-extracting crank arm bolts, and don't worry, I'm getting them in far enough.