Both use a different master cylinder than the 1500's due to the larger pistons. This was discussed on another post. I see so many people that want to upgrade to the 2500 stuff and i have to wonder why did they get a 1500? When i was looking for my first second gen it had to be 4WD ex cab short bed 2500(8800) 5.9 gas and black in color with gray interior. Any other deviation was not acceptable. Took me a while but i finally found it on the other side of the state. My Indy ram took even longer to find.

 

the piston size on the Dana 44 2500 caliper is just slightly bigger than the 1500 caliper, however for the Dana 60 it uses either one much bigger or 2 small ones, I agree with the master cylinder, my truck started out a 1500 and because of the rot on the frame and the underside of the cab I decided to restore it from the ground up and the frame, coil, leaf springs and Dana 60 rear differential is 2500, the front diff is a Dana 44 which is used on both 1500 and 2500 trucks so instead of using the 3 bolt 5 lug wheel bearing and hubs I went with the 3 bolt 8 lug wheel bearing and hubs, was going to use 5 lug to 8 lug adapters but the front would stick out an inch further than the rear and didn’t want that

 

I’m running 2500LD front calipers with the stock 1500 disc & pads, and 2500HD rear cylinders with stock 1500 drum & shoes on my 98 1500 using the standard 1500 master cylinder and booster.
No issues, just better braking.

 

I took this same advice I found on here (maybe from one of your older posts) and upgraded my 98 brakes exactly the same as you about a year and a half ago,. I have not had any issues and brakes are much better.
I am wondering though, could I have used LD 2500 pads rather than the stock 1500 pads? Or are they the same? If I remember correctly, I was thinking the 1500 pads looked a little small with the 2500 caliper and i had extra room for a bigger pad.

 

There is the possibility that the 2500 pads are indeed larger, as the rotors are larger. However, with the 1500 rotors, real possibility that the additional size wouldn't even contact the rotor. The improvement comes from the larger piston in the 2500 calipers. Same pedal effort gives you more braking power.