Any significant difference, if possible, will not be easy. At the price point of the Volusia, you have to make some trade offs. Someone else may have some ideas, but I'm thinking maybe an anchor on a chain.
The anchor and chain idea might be a possibility. My other bike has abs, so that’s whe I’m coming from. I would have to ride 2 up to deploy the anchor, and I like riding solo. I save this for last resort.
The only thing you can do to improve the braking performance for the bike is to replace the brake line with a braided stainless steel line, then replace the organic brake pads and brake shoes with a set of sintered metal pads and shoes. The difference is slightly better initial bite and less fade, but it also increases the likelihood of locking one or both wheels in a panic stop.
You cannot swap a C90 fork in for the C50 and you cannot retrofit the back to accommodate a disc brake.
Has anyone had a good experience with a front pad "upgrade" on these bikes vs stockish organic pads? Less fade would be nice. I'm thinking of going with something "semi-sintered". Not interested in tearing up the rotor.
The common "upgrade" is to install the EBC sintered pads and shoes. I wouldn't worry about tearing up your rotor using them. I don't know anyone who's ever had to replace a rotor on a motorcycle because of wear. Same goes for the drum.
It's long been joked that the best upgrade for the C50s brakes is to buy a different bike.