Ignition adjustability options

I am running an MSD digital 6 ignition, MSD billet distributor, and H.O spark MSD coil, on my 410 small block.

I am looking for an option to retard and or advance the timing via a switch mode or an adjacent box to my existing MSD ignition, without having to mechanically advance of retard my distributor timing.

The reason is that I am running 10.30 with 36 degrees of timing. But would like to run different classes on the same night like 10.90.
Would like to slow or make the cast faster by adjusting my timing between the classes, without touching my distributor.

What options do I have to do this via any additional MSD box or application by MSD?