The 96 and 116 will work, but it's my opinion that the 90 gives the closest 'look' to your engraving that a hand sharpened graver gives on 18th an 19th Century work. The vee is deeper than the 116, and the cuts don't look so much like bright cut Western style concho engraving. There is nothing wrong with that style engraving, but it's just too 'bright' for a longrifle.
A '70' or a '80' degree cutter will work as well, but the points are slightly more fragile than a '90', since there is less metal supporting the cutting edge. These are better for shading cuts.
I hope you can see the image below, where the 90 is indicated.