You need at least 36 total. I run mine at 38.

Can you run 89 octane so far advanced?
So when i advance it at the top is it ok with the bottom naturally advancing itself as well?

It runs up to WOT sometimes with no problem, it does choke for fuel sometimes if you try to do mulitple fast runs. So im going to check the tank pick up this week.

The spec in merc manuals for engines similar to yours (400-420-440-460) is 36 total. I would think they keep it a little conservative. It will be fine at idle as long as it's not more than about 15-16. Idle speed will pick up so you may have to idle down the carb. What's timing at idle now? What ignition setup do you have now? Should be fine on 89. I trailer mine so I always get 92-93 on the road before ramping in.

Thanks for the help..
Im running a new hei distibuter
I forgot initial ill check next time i fire it up.
I run high octane and mid grade depending on how week went lol.