I was in a similar situation but different vehicle (long story) and ended up buying an air fuel ratio sensor and gauge off Amazon. While it was about 120 quid, when compared to repeat dyno sessions it's a cheaper alternative and you have a sensor and gauge to keep.
Either just shove it up the exhaust or cut a hole after collector box and brazed the collar on to fit the sensor (before any cat).
Works brilliantly and you can see the AFR in real-time as you're tuning and even while riding if fitted into the exhaust properly.
This way you can make adjustments to needle heights and see where it leans out in rev range and by how much.
I don't know if you want to go this route, but I learnt more about carbs in that one tune up than I have in over 20 years riding, so you could use it as a learning curve too