By the time you buy a new Valley, and new rails, and good cloth, you are probably at the cost of, or more than a new Diamond and while your Valley will play better, it will never play like a Diamond due to the shelf depth.
I play in two leagues, both with 8 tables, and up to this year, one had Diamonds, and one Valleys with ridgeback rails and Championship cloth. The Valleys played really good for Valleys, but they weren't Diamonds. The place with the Valleys pulled them out and brought in all new Diamonds this year. Even with the Ridgeback rails and Championship cloth, there still was a notable difference in how the Valleys played.
I think as you already have it, you should enjoy it for what it is, a fun table. You can put a good cloth on to make it better if you want. If you play leagues or weekend tournaments on Valleys where you are, Then a Valley for home was an ok choice.