I got this R500 from the recycle bin where I work. My friend/boss said that if I could fix it, I could have it.

Well... I fixed it!

There wasn't anything really wrong with it. Just a clogged cooling system, an easy fix. It had no HDD or RAM. That had already been pulled. I have no idea what the original config was, but it did have the C2D P8600 CPU and WSXGA+ screen. I have since upgraded it to C2D T9900 (from a Dell Latitude E6400), 8GB RAM (2x4GB DDR3, from 2 HP AiO desktops, 1 from each), and an older Samsung 128GB SSD (from a ToughBook CF52, originally from an HP). It runs Windows 7 Pro x64 perfectly fine. I tried Windows 10 Pro x64 and it worked as well, but I reverted to 7 because I didn't much like 10. Not bad for a recycle bin pick n fix I say.
My question is should I leave well enough alone or swap the motherboard for the ATI Radeon HD 3470 one, p/n 42W7983 or p/n 42W8108? I know I'd need the HSF p/n 44C0800 as well. I'm also considering trading it, minus the SSD, for a T500 in good working order without its HDD.
On a side note, at where I work, I have 6 ThinkPads I'm refurbing for resale. 3 T43 14", 1 T60 14", 1 T60 15", 1 Z60t 14". Where should I list those?
*Edit: I forgot to include that I flashed Middleton BIOS (7YET79WW) and added the wifi card from a parts T420 (Advanced-N 6300, p/n 60Y3193).