The character in question can do the damage suggested without using either the cyclops helm or the scarab, so i don’t view those as critical to the justification of the original post.
Which is why I said "in a somewhat reliable way,". Name Violation's original post was about Vital Strike being good, and if you can't do it reliably, it's not good. Overkilling a mook by 250 damage instead of by 30 damage doesn't make your character any better, it's the boss fight you need to do it in. So yes, there's a 4.75% chance that it would one-shot a boss. A Wizard casting Phantasmal Killer has a higher chance of doing that...