You've already received a pretty good list of other chores to take care of while the tractor is apart.
As for the actual ring replacement, many will say heat the ring up in the oven first. That method is not available to me....wife won't hear of it.
I tried heating it with my oxy-acetylene torch, but it's hard to get it uniformly hot....I ended up having one part hot while the other parts got cool.
I finally had good success by building a small fire in the outdoor firepit, then putting the ring in the coals after the fire had burned down some. After about 15 minutes in the fire it was glowing hot all the way around. I picked it out of the coals with a couple of channel-lock pliers and dropped it onto the flywheel.
I've also heard that a gas barbecue grill will work, but I haven't tried that yet.