Well there is a chance that the skarboyz could win, one they out number the honor guard by 10, if the orks have sluggas and a choppa they get +1 attack and if they charged they'd get another which gives them 4 attacks each. Sooooo they'de have a chance. Althought the honor guards stats are better the orks have greater numbers. But it would be close, VERY close.
But you have to remember most people wont just use one squad against another, they'll be pelting the orks with whirlwinds and other ranged weapons while attacking with the sqauds.