WOW. Replacing a motherboard?!? You have talent and moxy.
You can place ANY Storm 9530 compatible OS in your Storm if you have the stock motherboard I suppose. I suggest the most current 5.0 build. I believe there is one you can download from the tip of this 9500 series forum. Just use the apploader to install your OS. There are instructions in that thread on how to upload the OS to your Storm.
http://www.blackberryforums.com/gene...ilanguage.html
Once you load the OS, just search the forum for how to get it to run on Tmo. A Google search will work too. But you are using a phone that RIM no longer supports so be aware you will not be upgrading it any further after you get it up and running.