I currently own several rifles a couple of which are the Bren 2MS and I have chosen my 14"sbr as my primary go to/shtf rifle. What spare parts should I acquire to keep it up and running.

I would say the usual bolt parts: firing pins, ejectors, extractors and all the pins and springs thereof. All of which have been in short supply since day one. The crudded-up / mangled oem ejector spring on new Bren 2s from the factory has been a pretty common reliability issue.
Unfortunately, parts availability from cz usa has been sporadic at best, which is unforgivable. After 3 years of searching I just now finally got some spare extractors and springs — from HBI!!! So kudos again to HBI coming through on the Bren 2 as CZ repeatedly drops the ball. I wish HBI could carry all the Bren 2 parts.