With big lumps of heat conducting metal as a manifold, you'll need this.https://www.autosport.com.au/weber-soft-mount-kit
It'll also help with vibration damping/fuel frothing a little.
Although not as pretty, tubes with rubber hose type connections and
a mated manifold on the carb side, are far more practical.
But, looking at the bike it's going on, it probably won't make a difference.
Allan, blending the head like that actually spoils the squish effect to some extent
especially when using the big bore kits.