Options...........
Buy a blank front sight from Brownell's.
These are made over sized so you can file to fit.
https://www.brownells.com/search/?page=1&search=blank+front+sightTo finish, use Brownell's Dicropan T4. This is a cold blue that gives a Black color that more closely matches modern gun bluing.
It's also the most durable I ever used.
Tighten the fit by dimpling the slide dovetail or the bottom of the sight.
To do this use a slightly dulled center punch to raise craters or burrs. The usual is to do the slide, but if you can arrange things it's better to dimple the bottom of the sight.... this follows the gunsmith standard of altering the part that's cheapest/easiest to replace if things go wrong.
Use Loctite Red or a high grade one hour epoxy to glue the sight in place. This avoids all the risk and trouble of the first two options.