That gun was originally sold by Ruger in it's ONLY config, with a 6-1/2" bbl, and probably blued - so it was modified after it left Southport.
While Ruger themselves did no chrome plating, they DID have a few guns chrome plated at a plating firm across the street from the Southport plant - but documentation's iffy.
The OP gun is a totally aftermarket custom, exhibiting a poor-to-middling prep job (polishing) prior to plating - a big deduction in value, putting the gun in the "shooter" class. ($400-$500 max)
BTW - Ruger did make 4-5/8" .44mag SBH's, but all were New Models.