This might be of some use. I forget where I got it, I take not credit for putting it together. See attached image.

Keep in mind that you can change the port timing for higher top end but you may sacrifice a stable low end or smooth acceleration. Sometimes the wide open exhaust duratiation numbers are for a tuned pipe. That will give more time for the pulse to come back into the jug. Things like how the gasses flow and their interia have to be consitered. If you do make a port wider be sure and avoid making the top and bottom flat. You can catch the ring if you make it too wide and don't make it eliptical. Gringind on the ports disturbs the nickasil liner and you might have it flake off. Polishing ports all mirror shiny is not as good an idea as it souds, it can do harm. It is all vey confusing to me. I was able to get respectable number out of a Featherlite weedeater this way. Later I went too far and messed it up. That is the problem for me, "too far" if an invisible cliff. Oh, throwing the jug gasket away alters port timing. That may do more harm than the increased compression gains.