could this be a decent lld armour ?

no

well, that's a no

well.... do you guys have a guide or smth

Don't have a guide, but you can think about whether you would use those items for lld.
Would you put in 100 str into an armor that would have the same def if it was a mageplate that requires lvl 25 and 55 str?
How would the +3 mana help you in any way? Or the magic dmg reduced by 1? If you really desire the cold res, why not get one that has a higher value?

Same for the belt. The +30 to a single res affix requires lvl 13, so why would anyone want +9 fire res? or the +1 light radius?

Thanks for your time and the anwser

You have a good point.

How about the information u got on how high the abillities can get on the specific item lvl ?

Thanks for the help!

It's a german website about d2 legacy, but i guess most or all of the abilities at specific levels remain the same.
I will send you the link via pm ( idk if i am allowd to post it here )

When it comes to LLD, unless you have something that has rolled absolutely insane stats, sockets will be superior. a 3os light plate with a max hp roll is way better than this