Late reply, but thought I'd mention the FWF
stretch plastron:
https://www.fencewithfun.com/Shop-E/...p-E/index.html
Available in both 350N and 800N.
(Note: I have no personal experience of FWF kit, but it's definitely one of the few brands I would consider if I had to replace my kit. Just thought I'd mention their plastron...)