Strictly a custom proposition. Took a factory MKIV front sight, milled a channel on the underside for where the factory cross pin connects on the LCR, then drilled and tapped for the MKIV sight screw.
If the regular fixed sight LCR fronts fit your 3”, there are a few factory options for a fiber optic.
HIVIZ Ruger LCR Front Sight https://a.co/d/d2jd84M
Ameriglo or fission need to come out with LCR sight! A rugged adjustable rear from factory would be good upgrade.
I personally just didn't care for the Hi-Viz. I know they have a huge following, but I found I could pick up the orange XS sights (same set as on my .22 LCR and .327 LCR) faster and more consistently.
I also found the POA/POI better for me, holding about an inch below the X on a B8 target using my 147 gr handloads. 10 yards and beyond I use a 6 o'clock hold on the black. Please take into account I'm pushing 70 and wear trifocals...
The HiViz POA/POI ... IIRC I had to hold about 1 inch lower than the XS.
The great thing about LCR's is that it takes less than 10 minutes to swap out the front sights.
From my XS order: Non-Tritium Revolver Front Sight - Ruger RP-0014N-1N Fit: Ruger LCR (.22/.327/9mm), Color: Orange
Just one old guy's opinion.