Triple monitor arm length for 27 inch

Hi,

I need to purchase shorter side arms for my 27 inch triple screen monitor arms because of limited space, I have ordered a discount one that has 880mm sidearms. So I need to purchase shorter aluminium profile.

I see that 500mm/580mm is the standard on the lighter monitor mount stands. But what is the minimum length for a triple 27 inch sidearms so there is enough room to swivel and mount them. Would the 500mm be long enough or should it be 600mm ?

I have LG 850GP-B monitors the angle would be 45-65 depending how long the arms I can have.