I also used the Lokar dipstick with my 4L65e and wondered if the markings were correct. After filling it to the full mark and checking it while idling in the driveway it was good. However after taking it for a ride the level was way low. I had to add another 1.5 quarts. I don’t thing the converter got filled up from just idling. I talked to a local tranny shop, they said the correct fluid level is at the top of the pan at the gasket.
My latest issues is the converter clutch doesn’t always lock up.