You could use the legacy converter.
It transforms all legacy items into powerkits, this will reduce the overall number of items by 15-40%.
But be sure befor you do that that you equip on the mechs rhe items you wanna keep Ex: 1kg teleports, 4,8,12 kg shields, 2use hooks and charges and teleports, push wepons like bully etc.
If you equip them they wont be transformed.
Trust me you wanna keep those.
Be carefull when using the legacy converter.