Were it me, I'd source a stock air box and put that on with a K&N filter.
Next I'd find out what parts were changed in the carbs, and verify the float bowl fuel level with the clear tube method. Restore stock parts if what is there is aftermarket.
Sand or bead blast the spark plugs to get them clean, or get new ones.
Perform the entire tune up check list.
If a dyno is out of the question, then mark throttle and use a test track to check plug deposits at WOT, then adjust needle height with part throttle under load (reading plugs to either raise or lower the needles).
Lastly, tweak the pilot screws to get proper throttle response under load with 1/2 throttle twist at idle in top gear. (assumes Keihin pilot jets installed).
This all assumes you want a well mannered street bike, rather than one for race track only.
Cheers,
