Ok, the Mikuni 34 mm TM's are moved in close for rider clearance,9 inches from the carburetor airhorn to intake valve. Any closer and the wide carb body hits the frame parts.
The velocity stacks might be around 3-5 inches.I will make them from thin wall steel tube and hammer form the rolled entry ...
Question, the Mikuni air horn is 2-1/4 inches in diameter. Should the stacks be the same diameter or smaller diameter with a flared end to fit the airhorn? There's air metering openings around the edge of the air horn that need to be considered...The tuning link by Ron states length is more important than diameter.
I got the ignition disaster temporarily patched up.The Tomasselli dual cable throttle pulls the carbs wide open with a touch more than 1/4 turn.....Out of the box I changed the pilot jets to a #20 , lowered the needle to the leanest position,#240 main jets. The bike starts one or two kicks cold, one when warm, and settles down to a lopey but steady 1000 rpm idle. And I never touched the idle mixture screws. Blipping the throttle is instant response without black smoke or orange flames of a rich mixture. This is not an indication of proper tuning but at least it's a reasonable starting point.

79 T140D, 96 900M Ducati ....On a bike you can out run the demons..