Supposedly, the Performance Center offerrings use a 3/8" dovetail for the front sight. Part #24328 from S&W should be the correct part for a 627 V-Comp PC.
There may be gold/brass beaded or fiber optic offerrings with the 3/8" dovetail from Marbles and other manufacturers, but note, most of these will have a 'rounded' contour for the top of the front sight.
Pinnacle Guns in PA has a service where they will drill the factory front sight to accept a fiber optic rod. Just have to push out the sight and mail it in. Cost should be less than $40.