how to install a new valve body in tub and shower

After removing and disposing of my old tub and shower fixtures, I discoved that the new valve body instructions show the water pipes coming up from the slab and connecting. My water pipes come down from the attic and I would have to turn the valve body upside down to install.Is that ok or will it mess up the way the water is diverted from tub spout to shower? This a three handle fixture.

don

Some valves can flip their guts around. If you can't do that, your hot and cold would be reversed...best to just run the water around and come in from where it was designed.

valve

A three handle valve has a positive shutoff for the shower/tub ports so inverting it will not cause the problem with water from the shower head would if you used a diverter spout. If you use lever handles you will want to reverse them so they operate in the proper direction. The hot and cold will not be reversed. But, a three handle valve is no longer "legal" for a shower unless it has a pressure balancing unit installed with it.