shower faucet conversion

I have a built in shower faucet system that has had a problem with handles breaking even after several “universal” replacements. I would like to convert the whole thing to a “vintage” type where the plumbing is exposed on the inside of the shower. The problem is that there is no access to the present unit without removing tile. Is there a way to remove the valves etc., fron the current unit and attach the new unit to the existing plumbing? Thanks1