This is indeed a Lorenz. It is actually a more uncommon version in that it is a commercial variant of the Muster 1862 Rifle-Musket and not the more common Muster 1854 Rifle-Musket. The main difference is that the lock of the M1854 has a shoulder in front of the bolster which is not present on the M1862. The lock shape of the M1862 is often compared to the British P1853 series and referred to as "Enfield shaped".
True Muster 1862 Rifle-Muskets were made at the Austrian government arsenal in Vienna. The parts are fully interchangeable, where as the M1854 was hand made and the parts will not interchange. Your musket is a commercial version of the M1862, so it was a lock of the new shape, but it was contractor and not interchangeable. If you look carefully at the lock you will notice some circles on its face; these are plugged holes that show the lock was originally from an Austrian M1842 musket, or one of the other tube lock or even older flintlocks. The contractor who made this gun recycled and reprofiled the old lock on this musket. The stock also lacks the cheek rest found on guns built for the Austrian government. This was a cost saving measure found on some export guns that allowed the stocker to used a thinner slab of wood. Lastly, though your musket now has a smoothbore it was likely finished with a nominally .58 caliber bore with 4 groove rifling.