I have done some mild port work to mine and assembled it to see how it reacted. I added way more intake duration than I wanted....and when it was new the intake duration was actually higher than what I run in almost everything I have.
There was something wrong with the skirt of the piston that caused it to get caught on the floor of the intake port that I had to grind off.
It does have a small issue. I haven't figured out what is causing it yet, but it acts like it has an air leak. Idles great, turn it on its side and it idles poorly. I plan on tearing it back down before it's all over with. Current build has new parts: bearings, seals, cylinder, piston, carb kit.
Update:
Oddly enough the problem was a leaking high speed jet.