In reply to mseyunni:
Using a C/C++ refernce model is very easy, because you can connect it through the DPI directly to your UVM testbench.
If you have Matlab models you cann connect them also directly to a UVM testbench.
Regarding all the other stuff you should try to remove it completely because the pattern Generation, based on sequences and sequence items might completely differ from the current Approach.
If you are using a UVM Framework Generator you will save a huge amount of time. My estimates are between 6 and 8 man weeks.