I've never bought a new carb for an N. And, given the price & quality work they do, I just have carbs rebuilt by:
Automotive Manufacturers Inc
2400 N Lombardy St Richmond, VA 23220
They do mail order work. And they also rebuild clutches, pressure plates, water pumps, alternators, generators, starters & reline brakes.
By the time you buy a complete carb kit & the cleaning solvent, the $80 they charge for a rebuild is worth it.