If you're going to run springs that are larger than about 1.580, and installed heights taller than about 1.950....... And the T&D system you're considering is the "single shaft" set-up, then you'll more than likely have to do some relieving of the rockers to clear the springs/retainers.
The HS rockers clear 1.625 springs with no issues.
If I remember right Harland Sharp will also clearance the rockers for more if asked to do so.
