I’ve actually played with Victory and indexing. There’s a few problems to solve.

There’s no cable tension adjustment.

The RD cable pull to movement ration is off, at least with the levers I tried (record, 105 1055, dura ace 7400).

Synchro rings have designations for each color, but experimentation is needed to make sure they actually work.

Victory has a kind of b-screw adjustment without the b-screw, but the top pulley doesn’t get as close to the cogs. You end up with clunky (technical term) shifting.

If you don’t have to move the rear hub lock nuts you’re good to go. Otherwise the rear wheel might need re-dishing.

Overall I think the Victory RD does better with friction shifters.

So, the advice above to buy a shimano RD and shifters is probably the best way to go. Changing to shimano cogs with chain assist will result in even be better shifting. Think HG or UG.

Unless you really like tinkering with your drive-train instead of riding it...