When it comes to 8-point gates, you have several choices. For example, you could do a straight up octagon, an octagon with shallower points for UDLR. Sanwa makes a gate for their recent GTX restrictors (the red one (https://www.tops-game.jp/products/detail.php?product_id=7325)) that has zero indent but two little ridges that the stick activator settles into. They all feel subtly different, but my preference is the dented square. This is basically a square gate with dents on the UDLR compass points.
I recently made one for the LS-22 / Neo Geo joystick, and I thought the detailed drawing for it might be useful for anyone wanting to make a similar gate.
Gate-DentedSquare.jpg
Gate-DentedSquare.png
It's not strictly necessary to have the UDLR dents match the radius of the diagonal corners, nor is it a requirement that the depths from centre be the same. In the design above, the UDLR dents are shallower than the corners.
Both the corners and the dents are smaller than the activator (R3 vs R5.4) so it settles on two points, not flush with the curve.
There are many ways to make these gates.