I hope this is not dumb, but is the replacement for aesthetic purposes?
If so, why not just clad existing steel columns with timber (recycled or otherwise if appropriate), maybe less work and expense.
Oh dear,
If your asking this question now , maybe you should scrap the racks and buy some from someone knows what they are doing.
As stated previously you need to consider: materials and grade, sections, construction, height, shelf span and spacing, bracing, is the application critical, how are...
I don't if this will be of help but I've done something similar on a much smaller scale (1 tonne out of balance on a 7 tonne counterweighted vertical door). I assume you have rope drum driven by a brakemotor and gearbox arrangement to lift this beast. On the "down" cycle, try back...
You could try a local manufacturer of industrial paint/adhesive mixing equipment, but be prepared to pay!
Many years ago I use to work for one such co. in Sydney and designed several vacuum vessels w/cavitation dispersers and perimeter mixer/wipers from lab size up. If you can't find a local one...