Unless dual star has changed the kit they have waaaaay more shims you won't need than the kit Fred sells. Double check before you buy! I've put a few of the 270's in, but really rare, and that's the biggest shim you might ever need, IMHO. I've used a few 265's, a fair amount of 260's, and lots of 255, 250, 245, and a fair amount of 240's. Even put in a few 235's. Often the shims are shhuffled from one position to another, if they aren't all the same (or too close to the same) in your motor. People often ask what stock sizes are. I've seen from 275 down to 250. Majority seems to be 270 down to 260.
all the best,
Edit: I just looked at the dual star site - they supply 2 each of the 280, 290 300, and 310 sizes in the kit. IMHO, there is NO WAY those will be used in the KLR650. The only way would be if the head is rebuilt with shorter valves in it.