You should be fine with that. 8.0 for iron, 8.5 for aluminum is the general rule of thumb. But some combos may work better so they could accept higher DCR and vise versa. I'm at 8.0 with iron heads and run 91 with 28 degrees total timing. The engine might take more timing on 91 without issues, but I haven't tried it beyond that without race fuel. And for plugs, I've been running NGK-7 around town and track. That's about as hot of a plug as I want to run. NGK-8 or -9 would probably be better at the track in my situation.