Never heard of anyone changing drums. Of the handful of those that have made this work, they simply had the rim of the drum that interfers with the wheel shaved at a brake shop. Only need to take off an 1/8" or so and the area is not structural.
You may also find the rims hit the ball joints and/or tie rod ends on the front (check when turning lock to lock, too). I've heard that can be fixed by grinding off just a tad of the joint with a hand grinder.
Some say "no problems", others won't risk it. I almost did as you are considering, but decided to just buy rims that fit. A long-time car/truck salesman I know mentioned that if you ever got in a wreck and there was some indication it was brake related, your mods may leave you liable. Kind of a stretch, but something to consider.
-Jay