I respectfully disagree with Cal30 1906 about the 480 being a novelty. I have a 454, some 45's, and a couple of .480's. Including two Super Redhawks.
They are very accurate handguns. they also do not have the "snappy" sharper recoil of the 454. Their recoil is more of a "pushing" recoil. I actually prefer the .480's over the .454 for fun shooting.
You've already said you were going to reload,, so ammo won't be an issue.
And I'll say that many years ago,,, owning a few Security-Six Rugers,, I didn't see any reason to get a GP-100. Until I handled & then shot a Match Champion. Now I own (3) GP's.
And when the .480 came out,, again, I didn't see any need or whatever for one. As Cal30 1906 said I too thought of them as a novelty. Until I shot one. Now, I also own (3) of them.
Both guns surprised me in how they performed. So I again offer my meager suggestion of just buying the .480 & keeping the GP.