I found a cool little thing to do with the big bore kits is a compression test. Unfortunately I have no clue what the numbers were, or even if they work with other bikes of the same model - you've got a fresh engine, you can pick up an inexpensive compression guage for about 20-25 bucks at the autoparts store.
Check it new and fresh and get a baseline number. Then you can check it again in the future to see when it has dropped off 5%, 10% etc, in compression...
This might be cheating, but when you're riding a bike a lot, you don't really notice the power slowly starting to slip away... the big bore kits run GREAT, but they go through rings pretty regularly. I've had Eric do a KTM125 (144cc), RM125 (144cc), CR125 (133cc) and all ran really well - but ring life is pretty slim as he mentions on his site.
I just would check the numbers from time to time (compression) and that would give me an idea of sorts about when I might need rings.
No joke, my pistons lasted FOREVER in the bikes though. I think I changed one in the KTM once, just because... well just because. It mic'd out okay though.
Have fun with the jetting. All the bikes I've had done, were a nightmare to get done. I live at 1300 feet which didn't help and it's winter time and they are selling us crappy gas... the nearest race fuel was 2.5 hours away so we had to try and figure out a setting that would allow for decent everything - they always spooged with the crappy gas though.
You'll dig the engine.
MP