cam duration

Going back over all of the posts, I went back to my 10+ SCR 351C and drug out the cam specs. ICA is 60 ABDC as installed. That works out to a DCR of 8.3 or 8.4. I was not aggressive on ignition timing and had quench, and polished chambers, and ran on pump premium, with no issues. So an 8:1 DCR limit seems quite reasonable to me with some modest amount of tuning care for 91 fuel.

So making some assumptions on the OP's engine (360 engine assumed with 9.5 SCR), and a Lunati Voodoo cam series, the 213/220 PN 10200701 ends up at 8.0:1. And in the Lunati High Efficiency cam series, the 210/210 ends up at 7.9 DCR. These are both if installed straight up, no extra advance beyond what is ground in. Both work out to around 60 intake closing angle. This all lines up well with the numbers AJ is tossing out there.

The above are both hydraulic flat tappet cams. As Magnummopar indicates, if you want to move to roller, then you can go a bit narrower on duration and yet better lift.

And I personally wouldn't expect the guys at Lunati or Comp, or any cam maker for that matter, to help you push the duration down to being near to challenging the detonation limit; they just aren't going to go there, IMHO. The can't control what the end user does with it, and yet the cam maker can/will get blamed if you or I muck it up and whine about detonation.