You could get one of each size from Cousins and by trial and error fit the one best suited. Also a suitable set of hands ordered at the same time would leave a spare complete movement and a repaired clock for less than the ebay item.
I do and I know others that do too, but not everyone agrees.
Acetone breaks down dried oil better than naphta, but is nasty stuff and very flammable. I keep my bottle of it in the shed and oil put about 10 mils in a small jar to use inside
One Dip solution would be best, but its very expensive.
You will find there is no 'one way only' to do things, but many ways all with their pluses and minuses, you just need to choose the way that works best for you.
The most important thing is to check the endstone is actually clean before oiling and assembling