I picked up this same conversion kit from Keg Cowboy about a week ago. I'm in Houston so I just stopped by the store. I added a Perlick 525 and a 575. They were nice enough to install the faucets and lines for me.
Its very nice, as you would expect. But as someone else stated for a 2.5" you would need some kind of spacer and would need to seal it up so cold air doesn't escape from it.
What I would do is buy a new 3" tower and just add it to that. Its beer, you deserve to splurge a little