Advise needed in-out shower vlave

I want to replace a shower faucet on an old valve that turns on and off by pulling and pushing with a newer looking set. I have gone to several places around town but cannot find anything that works on this kind of valve. Are there converter kits that are available for this kind of problem. The current hardware is very old so I can't figure out the brand. It has a round face plate and a tear shaped handle. If you can't tell already I am a rookie at this.

You have a classic Moen Chateau. There is ABSOLUTELY NO SUCH THING as changing the operation to a different model, EXCEPT by opening the wall from the front or the rear, and soldering in a complete new valve body. You may chose any brand or model once you open the wall. Moen and Delta are respected brands.

Not what I wanted to hear but thanks for the help!

Moen

By "newer set" do you mean just a different appearance? If so, there are replacement trim sets in chrome, and polished brass which will fit it.