Nice score mate. Welcome to the land of quick sharpening and the temptation to mod or make knives.

Two tips I got told are:

1) Get some cheap trash knives and practice sharpening or modding on them, saves wrecking a good knife.
2) If you have a flat platen behind the belt you can stick a decent thickness of leather to it (think a sturdy belt or strop). Then when you press against it while sharpening it controls the amount of convexing you do.

Good luck and get posting some pics when you're ready.