It is a common misconception is that the "top tuner" knows much more than you. I ran into that situation often in engineering. Also, no one likes to say that they don't know. Modifying an engine is actually designing a NEW engine. To design a new engine you have to have a good knowledge of the physics involved (thermodynamics and acoustics), the chemistry (stoichiometry), the geometry (visualizing 3D flows) and metallurgy (metal strengths, densities and tribology) of all the things that make up a two stroke engine. It will also help to know the history of the two-stroke as regards what things have been tried and what doesn't work.
To become more educated, you can read the following books: Design and Simulation of TWO-STROKE ENGINES__Gordon P. Blair.pdf, Graham-Bell-Two-Stroke-Performance-Tuning.pdf, Philip Edward Irving - Tuning for speed_ performance motorcycle racing (1967).pdf, Two-Stroke TUNER’S HANDBOOK__Gordon Jennings.pdf. These books are not perfect but are a good starting point even if they are mostly motorcycle oriented. This is not a bad thing. Riding a bike allows one to learn the power of a two-stroke engine in a direct way. Being able to sense detonation, rich running, over heating is all very important in knowing how to run and get the most out of a two stroke. Also, learn how to operate an engine well. Watch any person starting an engine. If he battles to get it running he probably doesn't know much.
Gordon P. Blair's older book contained computer programs that other people have used to write their own programs on two-stroke engine operation. Apps like EngMod2T ($400) and MOTO (252 AUD) supposedly can tell you what area of your engine is lacking.
You need a dynamometer to measure the change in performance of any change you do to an engine. You also need to know how to test with it. An informative paper on dynamometers is THE SCALING OF PERFORMANCE AND LOSSES IN MINIATURE INTERNAL COMBUSTION ENGINES by Shyam Menon.
Engines like Novarossi now are highly refined so that the space for improvement is small. Back in 1972, an OS Max .20 engine had 0.27 hp. Now in 2019, an OS VZ-B .21 engine has 2.89 hp which is more than 10 times the power from the same engine size!
Finally, your best friend is Microsoft Excel. This single app has all the facilities to support two-stroke engine development. Each cell in a spreadsheet is a calculator and the most complicated calculations can be easily simplified by using multiple cells and clear labels of what the variables are and their units. Output trends can easily be graphed or charted so you can see what is happening with the numbers.
Its database capability allows quickly finding gems of information out of tons of seemingly useless data. Excel can draw live diagrams from active data. Also, getting help is a simple as asking the question in Google.