What are must-have accessories for 3P ISSF rifle?

[xmillionn]

I am purchasing a Pardini FR22 and accessories I have been offered include:
-Extra rear sights
-Extra tunnels
-Short and/or long barrel extension
-Elevation kit for rear and front sights
-Weight holder and weights
-Specialized case for this modular rifle

I can see the immediate benefit of having the extra rear sights and I will likely need the elevation kit because I have a big head. Does anyone have comments on these?

[KabalMSU]

For Pardini FR22 as 3P ISSF rifle I would buy extra rear stock assemblies with buttplates and cheek pieces first of all. AFAIK, Pardini also offers special case to store all the stuff together with the rifle.

- extra rear sights
- extra front sights
- elevation kits

are also must haves.