Swapping boot drive from older to new MP?

My Mac Pro 1.1 has picked a bad time to fail (mid project), so I picked up a new base 2012 Mac Pro tonight. It's loaded with Mountain Lion on a 1 TB hard drive.

To make life easier, I would like to just install the 125 gb SSD from my 1.1 (running 10.6.8) into the new Mac Pro, and thus have all my fonts and applications available, and under a stable operating system, and then migrate to the newer OS when I have time to mess with it. Is that a viable option with a 2012 machine?