Vintage cast iron tub with original plumbing - how to replace?

We have a 100-year old cast iron tub that is still in great shape and we'd like to re-use.
However, the external hot/cold controls and waste line have lost their ability to seal completely and are leaking.
We are having a hard time figuring out how we either:
1. seal the hole in the porcelain and use external fixtures put into the wall or
2. replace this external plumbing with something else utilizing the existing hole and existing lines?

Does anyone work on vintage tubs and have any recommendations on where to find fixtures or what approach to take? Thanks!