CCR527: I think the wording makes it pretty clear that an Encore or any other "break-open" gun is NOT legal. Looks like a "plunger-type" ignition is what they're after in an inline gun.
I am not real familiar with a lot of the guns, but the Whites would qualify, and others with that styl of action. I guess the Remington 700ML and the Ruger of the same style. (Dave - you are familiar with more of them, I'm sure.)
Otherwise,you could go with a sidelock - a Hawken or Renegade would be a good choice. Maybe you'dwant to get real traditional and get a flinter.