IIRC the big thing when using the MkIV alternator is you have to change the connector plug. I believe if you use the later alternators on an 82-83 car with the early alternator you have to install a diode or something to get the charge light off. I would try an early 90's MR2 turbo alternator. Supposedly its 100A and is a direct fit on a 7M, so it should be the same swap difficulty as a 7M factory alternator. As far as the pullies go yes you can switch them around as required. Your 83 should have the serpentines belt setup though, it started in 84.