Beautiful 16-4. And a 4” to boot. My .02 is to leave that sweetheart alone. 16’s are gaining in value and take it from someone who looks for them, they are not easy to find. The .327 federal is a long cartridge that holds a lot of powder. According to data I’ve read, it operates at about twice the pressure of a .32 H&R mag. You’d be creating a fire breather with that short barrel. Probably bad enough that it wouldn’t be fun to shoot. Yeah I get the reasoning behind multiple cartridges and all. Practice with the H&R, carry the .327.
Now for the economics. You would be taking a getting to be collectible 16-4, with a lot of value, and changing it to something else. You will spend a bunch of money to rechamber a revolver to another cartridge. You will hurt the value of a collectible. The barrel will still read .32 H&R Magnum. By the time you get done with the cost of gunsmithing, hit to value, why not go buy a GP100 from Ruger that was designed around the cartridge? You could I suppose have another cylinder made up for that revolver. But that again would cost plenty. And then there is the swap over PITA.
Leave that one alone and pick up another designed for the cartridge. Again my .02. I’m sure others will chime in.