benjamin welcome to the forum. It would not hurt to add fuel additive such as Castrol Valvemaster, one of Trusty experts should know for sure. It would also be well worth using something like Ethomix from Frost
I use Castrol Valvemaster additive in my Norton engined Trusty. You only need 1ml of additive per litre of unleaded petrol, so a bottle will last a very long time.