Hi Cake of Doom...
Two sayings come to mind when I read this... make that three...
1) A truss is a beam with the unnecessary parts of the web removed. (some professor at school)
2) When in doubt... make it stout. (my dad)
3) I wouldn't touch it with a ten foot pole. (ZZ Top)
I couldn't quite follow you on the location and number of these holes? One hole 840mm from the end of one beam out of how many how long supported where and holding up what for who?
I'll take saying number three please. (humor)
Sorry but that's something that only somebody with all the information can answer.
Good Luck,
Bob