G'day Ian, are you running offset hangers in your Ap?
http://www.summitracing.com/parts/DCC-4120077/
I'v got em in mine, but I still dont think i'd fit a 28x10.5 on a 10"rim. I run 275-60 hoosiers on 8's and it scrubbs bad on the street.
How stable are the 28x10.5's on 8's? I got a pair on Ebay for $100, Im gunna try em out soon.
Do you need more RPM in the topend? Is that why you want less rollout?
Oh and I was talkin to my cousin Glenn the other day, He told me he built the pipes on your Ap, small world hey.