I apologize for having 5 guys give you five varying answers, but I contend that if you're looking to go less complicated, subtracting two of the barrels is taking some out complication of it.
I cannot even find a carb rebuild kit online because I can't ID that carb from my chair.
Rochester dual jets were widely used and a carb kit can be found easily; might have to go online for an adapter to make fit on your manifold.
Of course every person here thinks they are correct, however I stand by that the only answer that truly makes your engine running a physically less complex task is switching to a very common and well understood two barrel: Rochester 2G
EDIT: I'd also like to point out that ANY new carb--including my idea--will require the fabrication of some type of throttle linkage. You really should consider a rebuild of your current unit unless you want to figure out how to fab linkages somewhere in the mountains.