From the articles above, I think that as long as the gun starts its life as a pistol instead of a rifle it would be classed as simply a 12" barrelled lever action pistol and thus NJ legal. Which is what she wants, the pistol not the short-barrelled rifle, so it would not have a shoulder mountable stock like the Mauser and Luger. The lever action and internal magazine would be the only functional difference between this and say a Thompson/Contender, that I can see. In other words, since you can have a AR pistol (Carbon15, OA-98), which is semi-auto, why not a lever action one?
The original '93 were in 25/20, 32/20 and 44/40, I think. I also saw one that was/is 38 WCF. The "replica" rifles on gunbroker seem to be 357/38, 45LC and 44/40. I wouldn't mind one in 357/38, and the JB Custom shop seems to have the "Mare's Leg" in those last 3 calibers for about $1500. It is custom, so I guess you're paying a premium for that work...
Any other thoughts?
BoBo
Edited for clarity