At 5'10" 140 you'll find most armors may be a little large on you but that's ok most can be altered to fit.
As for the suppliers you have 850 (North America), Jim's (Philippines), and I hear there's may be suppliers in the UK and Australia but don't quote me. No one else has come forward asking to have their armor added to vetted list that I'm aware of.
When working with Jim's kit it's not that it's harder to assemble you just need to be aware of the fiberglass and just make sure you're using the proper personal protection, like a respirator when sanding. Also, Jim's kit may require ongoing maintenance as it tends to have minor cracking issues as time goes on (someone correct me if this has changed).
Edit: I think KB makes a kit, check FB