Two very pertinent schools of thought....
1. Lube in front of the ball.
Positive - You can get a lot of lube in the weapon and the lube is in front of the ball enhancing the likelihood of good lubrication. Also, you don't need to buy or make wads with this method. Seals the chambers reducing the likelihood of gases passing from the discharged chamber to others not in battery.
Negatives - It is much more messy. The consistency of your lube becomes very critical since you really want it to stay put and if the lube is not very stable it will melt and run all over a hot revolver.
2. Lubed wad behind the ball
Positive - Very consistent lubrication and many say it is more than adequate to properly lube the shot. Much easier to load. Much less messy to load. Much more stable in a hot revolver or on a hot day. Seals the chambers reducing the likelihood of gases passing from the discharged chamber to others not in battery.
Negative - You have to buy or, better yet, make the wads. The wads take up space on the chamber which has to be considered in compression. Also a disadvantage if you like to load as heavy as possible (Few do).
I do not disagree with those who feel a strong anymous to one or the other method. I have not formed an opinion which I think is better. I have been doing the lube in front of the ball for a long time but I am thinking I should try the wads more often. Especially in BP cartridges.
I have no experience with and no opinion (That I am willing to defend publicly)of conversions.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson