Sounding good and suitably de-twanged, Norm.

If you can, get hold of some RWS Hobby and JSB RS. These tend to give higher outputs in lower tuned springers. If the power isn't uncomfortably close to the limit (doubting it will be), it sounds like you'll have plenty of scope to raise power by increasing the preload, if required. Maybe a 5mm increase to start with and then going in 2mm increments?