I just took a look at two of the motors - one w/the thrust washers and one without.  Both look to have the LT250r piston with the 'half moons' in the skirt and two rings.  Doesn't appear to be an RM250 piston but I can't tell if it's the RM bearing or not.  I'm guessing it won't make a difference regardless however, as it sounds like even with the RM bearing billet thrust washers are recommended.  Now I got to see if they keep these in stock locally.  The Suzuki dealers around here don't seem to carry a lot of the older stuff.