Personally- my 86' is cranking along fine with it's 70A alternator.

I'd replace the regulator/brush pack with a new Bosch. These alternators are pretty durable. But if you want an upgrade and are willing to make a new harness to go up to the battery- go with the 143A which will bolt right in. Those bring $65-100 used, plus a new regulator $25 and then plan another $40 for wiring.
If you're going to replace it- I'd go only with a rebuilt bosch. I wouldn't mess with any alternator shops. Factory sells them with a longer warrentee I believe. Depending on your local dealership- they can be same price or less than on-line.



Michael