Have you got a 3.0 spare or know where there is one then buy it then ig you have any oroblems with your 2.5 then change them over. That way you can run your 2.5 and spend your time ma'ing sure your spare 3.0 is clean and sorted ready for the transplant
There's loads of info on a dedicated gtv6 website called Gabinete Tecnico Seis Uves, C.B.
. There you will find some really useful info and those guys really know there stuff
Also the eagerly awaited jim kartalamakis book is available ,I got mine from ebay,will tell you all you need too know about the busso v6