[Kurt in NJ]

Most alternators have to be spun faster than the generator in order to make rated output.
Smaller than the stock generator pulley— this will make the stock fan spin faster than designed.
The GM alternator uses the same bearing in the front as model A.
The V8 generator has a much larger bearing designed for the fan load.
A local rebuilder told me that that delco alternator was the best ever made— easy and cheap to rebuild and lasts just long enough that the people wouldn’t be pissed off at the repeat failure and he would get the business of rebuilding again.
My experience is similar,after 50 years I had to replace a bearing on the model A,in 40 years I have rebuilt the GM alternator 3 times in my chevy truck.
The 6 blade truck fans move a lot of air.
The thick belts were not made to transmit a lot of power without a good amount of being wrapped around the pulley,the tension needed to keep the belt from slipping will put more strain on water pump bushings— you might have to change to pumps with ball bearings.
What problems are you trying to cure with modifications?