Changing Balancer Pulley

I'm changing water pumps on an old nailhead engine from the non-A/C type to the A/C type. They use different pulleys, I need advice on how to change the pulley on the balancer. I hope the balancer doesn't have to come off to change it.

 

There are 6 5/16" bolts holding the pulley on-that's all you need to do-

 

Thanks Dan, I hadn't taken a good look at it yet, was just wondering how hard this was going to be to do, that's great.