The Galloway hammer gave me light strikes, on my bobbed 856. I too left the standard hammer spring, and the Galloway trigger spring. The biggest issue I’m having is that there’s almost a lighted take up from the lighter trigger spring, then the fullness of the hammer spring kicks in, making a smooth trigger pull moderately difficult.
Definitely dry fire a bunch before pulling the side plate off, then cleaning and oiling everything. That did a ton to help the trigger pull.