LT, 6 3/4 inch intakes is waaaaaaaaaaaay tooooo much if I understand you post. Don't know what you researched to think that is appropriate. A second that would be more than enough for any temps you wanted to reach. JMHO, I would raise the grate to 3 inches above the bottom of the barrel to allow for ash accumulation. Do what you want but my suggestion is to go throught all the UDS pages and learn from everyone else's mistake and fixes.
my avatar swiped fatties from the plate....look how sorry he is.
NB Bandera with mods
Weber 22 .5" x 2, 26.75" x 1
UDS x 3
Created "The Great Spam Revelation of 2011."