I thought the M-520 was basically a fixed-sight M-28 made for the NY State Police, who chose another gun instead. The 520's were then sold on the civil market. They're N-frames, not L-frames.
Am I confused? The L-frames have names like 586, 686, 681, etc.
My optimum combat revolver is probably my M-66-3 in four-inch with Pachmayr Presentation grips. The Ruger GP-100 is heavier, but kicks less. Not really too bad to wear in the right holster. I prefer the balance of the GP to the M-686. I think it also holds up better over the long run with full loads.
Indoors, I load Plus P .38 ammo. Firing indoors without ear protection with full .357 ammo will not benefit your hearing.
For a concealed gun, the M-65 with three-inch bbl. seems good. Ditto for the Ruger Security-Six with 2.75-inch bbl. and round butt. That Model 19P for the Peruvian police that Joe Kent mentioned and the same basic thing as the Ladysmith M-65 are fine, too.
I prefer stainless steel.