How to test OpenSPARC CPU?
Depending on time-scales, you might want to consider RISC-V

They claim it is "better" than OpenSPARC and OpenRISC

They appear to have several efforts to make the design more widely available.

It is derived from the same thread as produced MIPS architectures. They claim to have 'tidied up' several issues with older RISC designs.

However, it does not look viable for a DIY machine build until 2015 at the earliest. 

As others have commented. your goal seems very ambitious. You might find it as interesting, and more rewarding to collaborate with the RISC-V efforts. If they are successful at producing a range of Open Source ISA's, you may find even more benefits than making a OpenSPARC T2.