December 19, 1923 to be exact. That would make the engine a 1924 model. It's not uncommon for engines to be replaced or to have a car assembled from parts. Post pictures of the body and power plant and someone can give you more detailed descriptions of what you have. Depending on the month your 26 chassis was built, there should be a number stamped on top of the RH frame rail. Lift the floorboard to see if it's there. If present, this would be the original engine number. The transmission should have wide low/high and brake pedals. It should also have bolt flanges at the top that would attach the trans (hogs head) to the back of a 26 engine.
Somewhere in it's life, the car was retitled with a different engine (number). This is good in that the title matches but not so good from a collector standpoint. It's going to be hard to get it straightened out if that's what you want.