I totally agree about poor fuel distribution on a 3-carb manifold with two dummy carbs mounted. We used to tinker with fuel distribution on multi-carb small block V-8's by running thermistors in the header tubes on the dyno and tweaking port shapes and jetting until the exhaust port temperatures started to match up under load. For an engine that's mostly designed to win trophies at the local show n' shine, putting a couple of dummy carbs on a 3-carb manifold is a quick and dirty method of getting to and from the show without a lot of backfiring and underhood fires. It's nowhere near as good as a properly set up original fuel system.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!