Upgrading WR250R Suspension

Hi There,
I've recently purchased a WR250X in the UK. 2012 bike with 2500miles on the clock.
Am looking to convert to WR250R and am interested in upgrading the suspension as I'm wanting to replace my 2018 WR250F with this bike as I just don't use it and will never be able to ride it to its fullest capabilities anymore.
Yes, I know they are totally different bikes and all the usual chalk and cheese comments but I just don't use it and at 51 I just want to do more adventure touring/green laning/touring the TET etc without the hassle of short service intervals etc.
I love Enduro but with my spring/summer riding being destroyed by Covid 19 etc I could do more with the money even though I won't sleep for a week after selling it!
Anyways, my point is I'm looking for solid advice about the best way to improve the suspension on the WR250R to be able to get the best out of the bike as it seems a tad soft at the mo. I hear the rear shock rebound damping is a bit suspect?
I'm 6ft about 165lbs without all my gear on about 180lbs with and around 220lbs with luggage etc. Running 14/49 gearing with MT21/D606 tyres.
I'm based in the UK so way out of the great back up in the States.
Very interested to hear what you guys reckon.

There is an entire sub-forum here specifically on suspension issues. As there is for tire selection and gearing selection.

Thank you