How to determine MGN12H rail length for Scaled Kossel Mini

Hey guys, I'm attempting to build a scaled up Kossel Mini (750mm/360mm) and am considering linear rails over wheels. However, I do not know the length of the rails for this scaled up version. 400mm rails are standard for the 600mm height version.

Is 500mm enough for 750mm as seen here : [www.aliexpress.com]

Or 600mm as seen here : [www.ebay.com]

Thanks for all your help.