Tom, already sent you a mail.

To all others, Jeremy's correct in that the 300 uses 2x dowels in each cylinder for location, just like the stock 250 cylinders. They are the standard part.

Oh Jeremy, you've obviously never worked on a Honda NZ110 air cooled thingy. Hmmm. M8 studs and 9mm holes in the cylinder make for interesting rebuilding. The difference between fitting it right and just fitting it was about 2hp. We fitted dowels to the race bike!