One thing you can do is to create a second volume in the hard drive and install Snow Leopard in that volume, so you don't have to downgrade Mac OS X. You have also the option to purchase Mac OS X Snow Leopard Server and install it on a virtual machine.
If you decide that first option, first create a volume with Disk Utility > http://pondini.org/OSX/DU3.html Then, insert the Snow Leopard DVD, hold the C key while your computer is starting and install Snow Leopard there, so you will be able to install the PowerPC app you need to run on the computer
...can't ... spend over 15k on soft and now can't use because some one decided not to use rosetta emulator on Mountain Lion [spell check ON]
No one "decided" not to include Rosetta in Mountain Lion.
When Apple migrated ALL of its new Macs from the PPC CPU platform to the Intel CPU platform in 2006, it licensed technology from a third party company (later acquired by IBM) that it used for seemless transparent emulation of PPC software on Intel Macs, that Apple called Rosetta.
Its license to continue to include Rosetta in new versions of OS X expired with Lion and now Mountain Lion.
Before Lion was even out the whole "Rosetta" thing was known, there were as in every new OS, charts and more about compatibility, updates to 3rd party drivers and programs and all the rest. Over two years ago. And those charts are easy to find and run across - people have done this for over a decade.
Some vendors were I think mis-guided and lulled into penny-wise but poor idea that OS 9 and "Carbon-based" code would be universal - instead of realizing the need to move to Intel Cocoa type framework, and just like the move Vista forced to 64-bit, 7 yrs ago, that drivers would also need to be 64-bit.
And the transition was slow, over long period of time, and you CAN dual boot any Mac Pro, and you SHOULD have always, not just for this now, a clone of the old system or kept on another drive. And to avoid carrying along those out out of date drivers and programs, a clean OS (Setup Assistant makes it faster and better).