Hi guys, I just bought a Tikka T3X Lite Compact 6.5 CM 20" Barrel. I am wanting to get one of these Iota stocks for it. But not sure what to put for the specifics. I have attached an image of the options I need to chose from. I tried googling it but didn’t trust the results I found. Any input would be greatly appreciated 
Hand - Right or left hand
Barrel Inlet - Some barrels are thicker than others so you’ll need to know how big of a channel you want cut in the stock. What barrel will you be putting on it?
Bottom Metal - This is the shape of the cutout they make for the metal trigger guard and mag well (bottom metal) that you’ll be using on the build. I would think you’d want factory T3x.
Length of Pull - 13.5” is the industry standard. If you’re over 6’ tall, you may feel more comfortable with a 14” or 14.5”. Some people just prefer a little longer distance between the trigger and butt pad.
Thank you Jim. I appreciate it. So if I am just planning on using the factory Tikka T3X Lite 20" CreedMoor barrel that it came with. Which option would I chose? Or would that be shooting me in the foot if I want to swap the barrel out later for say like an aftermarket 22 CreedMoor barrel later on? Or would that require a different stock entirely? I would love to be able to use this stock for for stock Tikka T3X Lite 20" 6.5 CM barrel and swap it out later for a nicer 22 creedmoor barrel while still using the Tikka T3X Lite action. Is that possible? If so, which barrel channel inlet would you recommend I choose and which bottom metal option should I choose? I am pretty sure I am going to keep the LOP at 13.5". Any help would be greatly appreciated. Thank you so much guys.
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Can someone help me pick which I should choose? I cannot seem to figure out where/how to measure this stupid thing 
Is it just me or is this seriously lacking information to determine which one it is? Also, is this even possible to do if the barrel still attached to the stock and I don’t have a digital caliper?