Hey, cool. Yeah, I'll be getting one of those!
Some 350's took less, like some out of cars. The 350 in my Caprice, as well as the LT-1 in the T/A took 4.5 quarts cuz of the teeny filter they put on those engines for whatever reason. Fortunately there's plenty of clearance for the larger filter. Hopefully there will be plenty for the super-sized version.
I once came across a Buick 350 that took only 4 quarts. And the 5.3 in my Avalanche takes 6 quarts. Keep adding until the dipstick says "full!"
Just got reminded... for a 6 quart V8, the Avalanche has the *tiniest* filter on it. Most GM 4's and 6's take bigger filters. What's up with that?