6L90 shift schedule - for diesel V8

Hi Guys,

I'm currently tuning a 6L90 that came out of a LSA engine Commadore (Aussie car).
My issue is that it is now fitted behind a V8 diesel (S/C 6.5)
The trans is shifting and I'm happy that it's not flaring the changes, but the shift points are all to high in the rev range.
The guys at work have given me some guidance, however the trans is reluctant to shit and hold the higher ratios i.e. 5th and 6th.
Is there a "go to" area in HP Tuner that I can lower the shifting RPMs?

There was a version of the 6L90 that was fitted behind the 6.6 Duramax engine in a Chev Express van, but I have yet to get my hands on this cal.

Any help would be warmly received

cheers