I have a Stihl 62cc engine that I converted. It was a labor intensive conversion, but it turned out very well and runs great. I was perusing the technical data and specifications for the Sthil 62cc, and the timing was listed as "X" millimeters before Top Dead Center. Just for grins, I got my degree wheel and dial indicator out and checked the numbers. Guess how many degrees it turned out to be.
28 degrees, just as Bill and TKG and Ralph have been telling us for years!
Of course it never hurts to experiment. There is an engine I build that uses an Echo 25cc crankshaft in an Echo 23.6cc engine. It very definitely prefers 24 degrees timing, while the stock Echo 23.6cc engine likes the more normal 28 degrees. An engine needing less advance is generally believed to be burning the fuel more efficiently all else being equal, and my Echo stroker engines do run very well. Who knows exactly why they like less timing..... Probably something to do with the increased piston dwell time at TDC with the longer stroke.
AV8TOR