I ended up buying a set for my 12' 300. They are doing the job well. The oem cap didn't not fit and the one it came with was 1.1 bar. I found that a cap from a 13' KX450F will fit, you can find those in a 1.8 bar.
Did you get the ones listed as 12/13 rads , for some reason they cost more and I'm sure I read on here somewhere the 11 and 12 rads are the same