I don't do cap & ball revolver shooting and I can't recall ever holding a Remington `58. So I don't know if there is the extra room to bore out the center of the cylinder to add a coil spring. Even if there is, would there be an issue with regard to keeping the cylinder aligned with no wobble as the cylinder rotates, the base pin/piston comes back as the cylinder rotates?
Akumabito's idea for a gas piston might be easier, for then you're not messing around with the base pin, nor are you drilling out the cylinder and frame to accommodate a recoil spring. It looks a little funky with the gas cylinder on top, but there would be less need to modify the revolver to try it out.