It would not have the flat top fuselage unless it was an AR-7 airplane. You don't have an ag fuselage.
Sorry but can't agree on this one.... I have one sitting in my shop that is definitely a flat top Ag model and the data plate says IA2.
I also have a second one built in 1960 and it is also 1A2
Neither have ever had the AG equipment installed. I have been blessed in owned several "A" model cubs.
All "A" model cubs were constructed so that they could accept all of the "Aerial application equipment". (That is what the A indicates) This did not mean that they had to. They all had the flat top with the metal hatch installed over the baggage area and no headliner.
If they left the factory with the seat installed they were shown under 1A2 and in standard category.
If the aircraft left the factory with the AG equipment installed it was most likely shown as being built under AR-7. It could still be equipped for passenger usage but would have to have the standard or dual category AWC issued.
Many were licensed in "dual category". (Typically issued later after being converted to the opposite configuration) Standard for having the rear seat in place and all AG equipment removed and Restricted for vice verse.
I have seen several "A" model cubs that have been modified to look like standard cubs. They put a stringer down the center of the back but always looked strange; or if wrecked they would replace the top deck with a standard type.
I have seen some complete fuselage replacements with a standard design as evidently nothing else was available. The data plate still says 18A. (This is a practice that could create a very large can of worms for someone during a "conformity" inspection. )
The fuselage in the photo is lacking all of the AG model parts from the upper longerons up. The photos are too fuzzy to see good detail.
It does have the added intermediate 3/8 inch tubing in all of the bays that originally came with the AG units but a few of the later cubs had these added along with metal bellies in the late 70s.
All of the replacement fuselages available now have these tubes added and they make for a much stronger frame.
I would guess this is a standard fuselage from a later (post 1976) vintage.
For what its worth; If it was a used fuselage, you might find an original serial number on a plate welded on under the instrument panel on the right side.
The comments about having issues getting a COA or even registered in the US are spot on. I think you are out of luck....
Your best bet may be to try and use it on an experimental. You'll have more fun anyway!
Best of Luck to Ya!