My night of league i had as a junior was 255, 245, 177 = 677
I was extremely happy with that on about a mid 170 average, but was unhappy to get so close to 700 and not get it, although i still required a 200 in the last.
i have since broken my high game with a 263 starting with 9 in a row and then :x :x :x missing the head pin!