Anytime you have humps or bumps you are going to scalp.
Being an old timer and using the old Gravely's you could add skies to the sides of the cutting deck.
The answer is to someway add side skies to the center of the deck. This will insure the deck will not scalp and make it float high on bumps and humps.
On my HRB Honda I added a small wheel on each side to stop this. I was afraid to drill, but I added the metal side strips, which was an add on.
No scalping.
I stated earlier about the staggered wheels on the old lawnboys. This idea was excellent.