I know Ground Up and a few others make an alternator conversion adapter set. You only really need a pigtail but going to a 12SI is easy. Im put a 90amp in my car with a serpentine pulley of a mid-80's big block truck along with the water pump pulley and crank pulley. It doesn't look original but most people don't even notice it at a quick look. No bracket changes are required either so it was a very easy conversion. No spring tensioner either and the power steering pump retains the V belt. I ran a similar conversion on my old pickup using all GM parts and it was a great thing. I ran extra lights, an electric dual fan set and a decent stereo with an amplifier and never had any power issues. It made my headlights brighter with the wipers and A/C on at the same time. The kit is $20 and you don't have to cut any wires so going back to factory later on is easy. If you don't care about staying original read up on alternators at
http://madelectrical.com/
They have the whole theory on how these charging systems are wired and how to modify them if you want to upgrade anything. It is all very good information to have. I actually printed this out along with some other diagrams and I put everything in a binder for my cars. It is good reference material. I wouldn't go 1-wire if there wasn't a need for it.