I think you are on the right track Rallyfinnen.. Our airplane engines do operate in the 7-10,000 rpm range mostly. There are some of us going higher with special engines etc.
The delay is the factor you are working on. This is where the code numbers have to be adjusted due to lag in the hall and processor as rpm's increase.. Good work on the theory by the way! You are definitly on the right track. Since you are able to test the rpm and lag differences with your scope, you have a better idea what's happening than those of us without testing equipment.

When you get the numbers correct and can post a downloadable hex file for the 16f628, please do so.

Alot of us, myself included have a hard time compiling the code to hex. There is a how-to on the website for those that understand the principles..I haven't the time to learn at the moment.
Nice work on the results! We need input like this for sure on the forum.. Thanks in advance for your time and efforts!

John