Congrats,now go build another.
I run Intl 15s but I think the smaller arms Lee uses are part of why his like the higher timing although I could be wrong.
I'd highly recommend getting at least another endbell set up with advanced timing. Even if it isn't race legal it will allow you to easily test more and less timing with the set-up you have. Advanced endbells are a great way to remove the variable of having a dud arm when experimenting with different advances on a certain set-up. For example you could have a fast 40* arm and want to try 44*s and if the new arm is a dud you'll think it's the timing whereas with a 4* advanced endbell you'll easily recognize if the additional timing was beneficial or not since you know exactly what was going on at 40*.
Also get yourself a notebook and keep detailed records on all changes. When you make a change, test it with a baseline ratio and then try others and see what happens.Its hard to believe but I saw a decent improvement in one of my 27 Lights just by going from a. 515" to .516" hole, but going to .517" was a mistake and I had to start over.
Last but not least is don't make too many big changes if you're not happy. Sometimes drastic changes can hurt. So it's best to learn what each change does and why, then make a note of it and so on. Also trying to figure out why a motor is a dud can teach you a lot more then getting lucky and throwing together a screamer. Everyone gets a rocket now and then, its the best guys are usually the ones who know why a combo turns out to be a dud .