I don't really know, Steve. I'm sort of guessing now, but get whatever you've got out of the system by purging it, then do a normal fill through the balance tank. I'd say leave the little therm/connector hose alone, pull the big hose at the manifold, the little hose at the radiator (bottom), and run it for a few secs. You may want to hide around the corner cause it will throw scalding hot water all over the place. 60 secs max!

Let it cool again, seal it all up, make sure it's NOT hot, and start with water again in the overflow tank while it's running. Either measure it so you'll know how much it's absorbed, or wing it with a hose. When it stops going down (the tank will bubble and act up as you're adding water) I'd let it heat cycle then test it again while running - never let the motor run for more than 2-3 mins, allowing at least 30 mins for cool down. If you're comfortable it's full THEN add your AF by either siphoning a small amount out of the overflow, or not putting that much in to start with.

A big word of caution though - I'm sure you know this. That water coming off the motor is scalding HOT, well above boiling. Please be very careful with cooling systems - I've seen the aftermath of a radiator block cracking/bursting into someone’s chest. For this reason I just let the motor cool between fills so I'm never working with a hot motor. And I NEVER fool with the radiator cap. In fact I never take them off.

This is one of those scarier parts of this biz IMHO, I've always had some phobia about the heat a big V8 can produce