I did upgrade to a 100 or 110 amy Balmar. Westerbeke can supply you with double pulleys for the crank , water pump, and alternator if you get the right one. ( only one )
It works well and with the 2 pulleys you don`t have to tighten it too much , thus minimizing side load.
Depending on where you are located , I might be able to help with some pricing on the pulleys and maybe the alternator too ( not sure ).
I look forward to hearing back