nast16, Liberty models do have more value but only if the gun is in "collector grade", meaning pristine condition. Otherwise, a Liberty model might bring about $50 more than a non-liberty model in the same condition. Your gun already has some wear and doesn't have the factory grips (pretty easy to find) so changing it to a cerakote finish probably won't devalue the gun any more than the same process on a normal Blackhawk.
Just a suggestion …. these older NM Blackhawks have a thinner transfer bar and a shorter top step on the hammer so if you decide to replace the hammer with a SBH hammer, you will need to replace the transfer bar with a current production thicker one or grind about .020" off the hammer's top step. Other than that, all other parts are interchangeable with current production models
Here's my Liberty 357 BH. It has a slight turn line on the cylinder that looks much worse in the photo than in reality: