Coupla years back a young mate of mine's "mate" bingled his Dyna , speedo on the bars model. a 2009 thing. Cosmetic wipeout as usual.
At the Indy repair shop ( I was not taking the job on from my home garage , too hard basket !) he had them put Wide Glide/Fatbob tank/speedo etc etc as part of the repair. The repair dragged out to 11 months because of it. Getting all the "correct" parts to eventually blend in. They had to extend wires etc.
I gave him ( them !) a low K's Km/H 2007 FXSTC Softail custom stock OEM speedo from my stockpile of parts for getting grey imports "complied".
Now this was not a Harley specialist shop but a "motorcycle shop" , hence my intervention at the time , speedo plus other parts. They had bought a speedo in new that was too fungen small diameter FFsake so I pulled their fat out the fire there. I also GAVE them some other small parts to get the bike back to him.
It was a prick of a job/conversion as you are finding out now. Looked good once done but the owner had no ride for a year.
For the tank... I see in the pics its still painted from the factory. Did you strip to bare metal or paint over the stock black? Did you do any special prep?
Looks like a nice paint job for a "Hom'er" good onya. Chip resistance of the paint on the road will be your telling time.
All very similar to my young mates 2009 Dyna. Gloss black with green ghost flames , came out lovely.
then a full paint correction with the right products and a DA!