Browning Gti NZP13 Front Sight Replacement?

Hey Fellas. I have a NZP13 Browning Gti 12ga. with the factory white bead sights on it. I want to change the front to a Hi-Vis Plastic sight.
I bought a Browning Spark II Hi-Vis for it, but the guns screw size is smaller in diameter than the Spark II's 3X0.5mm stud. Oddly enough the thread pitch looks the same, or so close as to not see a difference.

Anyone have any luck with this before? What screw size to shop for & type of sight did you end up with?

It's damn near impossible to find any info on the Gti, let alone parts. The big gun stores like MidwayUSA & MidwestGunWorks give zero search results.
Hell, Brownings own website has nothing on them! Even under the "Discontinued" models.

I've learned they only produced them from 89 to 94, & they are part of the Citori family (I think).