new alternator on old bike??

So i'm trying to figure out if i can put a new model alternator on an older bike ('87)? i'm sure it "can" be done....can somebody tell me what, if anything needs to be swapped as well? or if it's worth it? i really do want to put a few aftermarket electronics (lights mainly) but i've read that the old electrical system can't sustain aftermarket stuff. any info would be greatly appreciated. thanks.

Better head to the other sight for that answer. Gerry