These is what I do since I got this answer from master tuner Dennis Richey several years ago. Hope it helps as it has been to me.

AFM

Don’t confuse compression with pinch; Sleeve Pinch is not that important contrary to popular belief. The question is how well it seals as soon as the piston starts to close the exhaust port and if it holds compression after you roll it to top dead center.
Place a few drops of after run oil trough the top (removing plug), then place plug in place, then roll piston to top dead center and listen and look for air bubbles through exhaust port. If there’s none, then your engine still has compression, even if it has no pinch.
The fastest team motors we use, have zero pinch. I even had them run to over 140ºC and they have survived well. Though I certainly don't recommend it.
Dennis Richey
Richey Racing Engines