I should put a word of caution about the double cut burrs. I'd gently try it out by hand right off the bat instead of chucking it in a drill(if you were thinking in those terms) like a person may do with a stone. They are "sharp" when new. The weight of a drill may make it really cut quick and too deep.
That 375 muzzle cutter..........I'd change the order to a bigger one. I can measure or check the book from Brownells......get the big one so you can flat face any barrel even rifle. The big one does it all. They sell them separate like you got the 44 pilot separate from the kit. The smaller 375 (if that is the diameter) be small and leave ,sort of, like a rebated muzzle area instead of facing the whole face.
Like I said earlier.....the pilots run small.....maybe you'd rather get a 45 pilot and run it ,carefully, on a drill and file it to be just the right size for 44......unless you have shim stock that's real thin to wrap the pilot for a snug fit. I use copper or brass shim since in can engrave the rifling a tad when trying to insert the pilot wrapped in shimstock. Your burr may impede the insertion of the pilot. You may have to clear the way for the pilot and then face the muzzle then ever so slightly touch the end of the lands with the cherry or....get a 45 degree cutter and just put a nice little concentric crown to the muzzle.
If they(in the small print under the description) give an actuall diameter ,instead of the less accurate or vague caliber designation, you could see if the pilot would fit. Ifn you call and ask they would have a tech support measure the pilot so you could see if it would fit snug in your "bore" riding the lands. When you put the pilot in you'd "wiggle" it to see that there is no movement what so ever side to side.