I did that recenty, and made metal b pillar covers too.
I decided to cut them off when I discovered that there was a lot of rust accumulating in there between the spot welds and seam sealer.
seam sealer is not perfect it will expand and contract and over time can allow water into areas like this where water can get into unpainted unprotected metal and rust out the affected area I had to cut a lot of rust out anyways so I decided they were better off in the trash, and I shaved em.
the aforementioned spot welds were what keep the roof pan to the cab door frame,
If you are not an awsome sheetmetal welder I say dont do it.
I have a miller 185 with auto set so I cheated LOL.
Cut the drip rail while leaving at least 1/8 of it stickin out , then tack every few inches letting the mtal cool between spots, the metal should burn back a little, almost level if done at the right heat settings, repeat till done the whole edge, grind smooth and you shouldnt need to use any filler. Filler in any amount is a bad idea in this area with constant stresses on the windsheild and slamming of the doors.
here are some pics of the work done
not welded
I made my own b pillars , 14 guage, bulletproof lol