If I were to rfinish my Model 52, I would look at one of the one of the finishes that reduces friction. NP3 or CP-II would top my list, though I would also look into IonBond for a Model 52
Obviously you are going to have the property scratchings polished out
Decades ago (1990s ?) I had my Duty P220 refinished in NP3 and it gave wonderful performance and great protection from the elements (something our 52s will not need)
More recently, I had my personal P220 (The other one was departmental issue and had to be turned in) finished in CP-II
Prior to these new fangeled finished I was just using Hard Chrome from Accurate Plating and Weaponry, or factory nickel