cam duration

Call a cam company who knows what they're doing! Duration isn't the end all be all for determining if the engine will detonate or not. I'm sure others will correct me if I'm wrong, but what's more important is when the intake valve closes because that's when in the compression stroke the piston/cylinder actually starts building compression. In other words, an earlier intake closing point will build more cylinder pressure than a later one and be more prone to detonate. A legit cam company will be able to build you the right cam to fit your needs and put your dynamic compression right where you want it.

Do yourself a favor and play around with a dynamic compression calculator online and see how intake closing event changes dynamic compression.