nothing wrong with mitaka pistons mate
and well done on your first 2 stroke ,i would have done the crank seals while i was in there as it was stood for 15 years !
it will cost you big if it goes ,my mates has gone twice now once on his old engine then one that had been so called stored correctly .
you will love it when you get out on it
but id get a set of seals and do it right especially while the motor is out ,dont even know if you can get crank seals for them as ive not had an mc16
see what others say about it ?