Soooo I replaced the rough in valves for my shower ( based on some suggestions here actually ). This is the set that I purchased. Now that it's installed, I'm noticing that the stems are shorter than the old one by about an inch. I'm also super confused about what kind of trim kit I need. Was looking at something like this but it seems to have both valve stems and handles, and I really don't need the stems ( right ? ). Then there is something like this but it includes the whole build kit. So I'm super confused about what I need to finish this rough in kit.
Look at the bottom of the Amazon page where it says "customers also bought this" there's trim kits there that have exactly what you're missing. Pretty typical for a contractor to use a rough in kit like you did and then let the customer pick a trim kit later. The only problem you have is you're limited to trim kits that work with the 01-31XA valve body. You should be able to find one you like. Here's one Pfister 01-8CBC Three-Handle Tub and Shower Combo, Chrome Fits 01-31XA valve body The Pfister Three-Handle Tub and Shower Trim Kit comes with classic Brass Cross Handles, flanges, bell-shaped shower head, and a threaded tub spout. The upgraded Polished Chrome finish and Brass Cross Handles is a great addition to any bathroom. Valves not included.
Your best bet is to uninstall that valve set and buy a complete faucet set. The valve set you have is if you needed to replace your valves you have and keep the original handles etc. A faucet set would have had everything you need and the proper sizes.