Re: incompatible lav/tub fixtures
It would be easier to change the sink fixtures than the tub because everything on a sink is accessible. With tub/showers, you've got to go inside the wall to change the fixture. The only thing you might be able to do besides replacing the entire valve is to see if A.S. has handles and escutcheons that are similar to the Kohler unit on the sink. If you do decide to replace the shower valve, then the wall will need to be opened up for access to the plumbing. The least expensive means would be if you can go in from the back and not have to demo the shower wall, otherwise you're looking at a new shower wall at least, if not a new surround, depending on the material.
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