As Porter has said, for the price ( assuming you can change the spring yourself ) may be worth a punt.
The next cheapest option is a revalve/respring. I had the std shock on my gen 1 Fazer 1000 done by MCT for about £275 ( a while ago admittedly ) and was very happy.
https://www.mctsuspension.uk/Darren would be worth a call, he may even be cheaper with more options for supplying just the spring

You may be able to get the right spring for your load from him, and then if it doesn't work out due to tired/ overworked damping , you will know you have the right one for a revalve later.
He is not all about Ohlins and huge money, and is good for a chat.