Pathfinder Archetype: Conversion of Musketeer (Cavalier archetype) to work with Samurai

One of the problems that I have with the alternate classes is that there aren't enough conversions of archetypes from the base class to the alternate. While I don't mind this so much for ninja/rogue and some of the paladin archetypes don't have a thematic reason to be converted to antipaladin, I'd like to see more conversions of cavalier archetypes to work with samurai.

Let's go with this one, a conversion of the Musketeer archetype for cavalier:

Tanegashima Expert: Samurai archetype

Loses heavy armor proficiency. Gains proficiency with firearms and can select fighter-only feats that specifically select firearms, such as Weapon Specialization

Gifted Firearm: replaces Mount, functions exactly as the feature of the same name for the Musketeer archetype for cavalier

Swift Powder: replaces Mounted Archer, functions exactly as the feature of the Musketeer

Must choose a specific type of firearm for Weapon Expertise instead of the usual weapons.