Hmmm... looking at the 3rd pix in the original post, the piston at the far right appears to have the valve pockets rotated 90 degrees from the normal orientation. WTF is up with that? And the valve pockets in the 2nd pix are also not in the right orientation. Sorry, you gotta see what is up there; I'd look underneath and then pull them. Something is definitely not right if I am seeing these pistons correctly.
No, it is not normal at all to have different pistons in an engine. Something is up and you need to partially tear it apart. Having the stock shim gaskets is meaningless as far as being a factory engine; someone could have just thrown it back together with old, used gaskets.
