I have run a mighty demon 825 and currently running an 800 thunder avs. On my 410, I would go with the 750 holley. You aren’t chasing every hp and the avs has a slight transition issue that I believe the AVS 2 is supposed to address. Don’t get me wrong, I like the avs, no fuel spill when changing jets, ease of changing rods, but you sound like you won’t be in there after it's set. You don’t need anything bigger than 750. Throttle response will be much better with a slightly to small carb.