Garandimal,
Why don't you just place a mark on the case neck of your brass corresponding to the base of whatever bullet you plan to shoot at whatever OAL you plan to load it to. Transfer this mark to the inside of the neck. Pour Varget into the case until it just covers that mark. Then pour that Varget out into your powder pan and weigh it. That'll be your 100% fill charge, and the actions described will only require a fraction of the time you've spent with this thread.
The answer you derive will of course have no relation to whether or not that is a safe charge to load but you have been pretty clear that all you care about is how much powder will fit under a bullet.
Rex
