modify stock pulley for HO alt?

[Xieo]

Hello friends, I am trying to install this HO alt i finally managed to source for my vehicle and the pulley that came with it is not correct. There is little chance the alt company is going to have the correct pulley. 

The stock pulley does not fit the HO alt due to the shaft being too short. The HO pulley is much more recessed towards the alt than the stock pulley. The end of the stock pulley that faces the alt is completely flat has a good 3/4 inch to an inch of solid material before the hollow part on inside of pulley. It will require a spacer to contact the HO alt shaft correctly.

My idea is to shave down the end of stock alt pulley about a quarter inch with a belt sander (bandsaw?) to clear enough room to thread the nut on the shaft of the HO alt and then use 2 or so spacers to get the length right for the belt and to space the pulley from alt body slightly. Will this work? will there be too much force on the pulley and shaft?

Do i have any other options here? Somehow get a custom pulley made? The alt does fit my car using some spacers but the longer stock pulley is stock for my make and model.

Pic of alts https://imgur.com/9LwpKMq