We want to replace the Delta fixtures in our tub/shower surround that date from 1977. Of course, that means the valve is also ancient. There are no signs of leaking or anything, but I realize we're probably on borrowed time. Since we want to have our fiberglass? acrylic? tub/shower surround refinished (also old but no cracks or chips, just dingey), would a plumber be able to replace the valve from the other side? There is a shared wall behind it covered in drywall.