It may be a Forehand Patent gun. H&A used the Forehand design after they bought'em out. It's a good action, paired with Twist barrels they make good Vintage Field Grade Shooters. 60% condition would be unusually high condition, the Case Coloring should be very vivid on the metal, and the barrel pattern should be 80% remaining. Remember, that's 60% of Original condition. I suspect the actual condition is lower, overstated probably because it's still in good mechanical shape.
Not considered especially collectable yet, I think I paid around $350 for one with fairly low original condition finishes, but still in good mechanical condition that was absent other major faults.
IMHO, $275-$350 would be the range for a gun with good mechanicals and no major faults, but lower if faults were present.
H&A, as well as Iver Johnson and a few others did make guns with false sideplates, there's a past thread about'em, but this gun doesn't sound like one of those.
A Forehand action looks like this:
http://img.photobucket.com/albums/v316/Ansleyone/053361.jpgRegards
Ken