OK, great....
Now I've technically said two things which aren't necessarily true...
I'll need to explain more...IF there is no valve overlap, both valves will be closed at TDC regardless of which stroke. But, that is rarely the case, particularly on motorcycles. Therefore, the amount of the overlap determines how far the valves are open when the piston is at TDC. The only thing we can say here and be totally accurate is, the valves will never be fully open at piston TDC, though they might be fully closed, again depending on the cam grind and valve overlap in particular.
My main point of my original post SHOULD HAVE BEEN:
you have .137" to play with to sort out your valve overlap with a new piston. A milder cam grind will give you more piston-to-valve clearance and a hotter cam will give you less for a given piston.
Therefore, if Lancer's setup works with a particular piston, so should everyone else's...
Not sure that's better, but its the best I've got today