Some help please?

[zipperkarting]

Hi
I'm currently running a Speads RS08 with 1300 Hayabusa just for Track Days.
My first outing was a disaster. I demolished the complete top end, I assume from downshifting at too high revs. Well at least that is what I was told.
My motor was a Powertune motor so I was a bit upset.
However I bought another stock 2006 motor having been told it was probably as quick as a 1999 Powertune.
It seems OK to me but I've just purchased a Powertune ported cylinder head with APE valves and adjustable cams that I want to fit on the stock bottom end.
Can anyone see any problem with this? Will it bolt straight on without further mods?
Also thinking about a slipper clutch as I assume this will help with the downshifting also. Any views on this would be appreciated.
Many thanks