I though about selling..now im thinking of cloning it.
I think you’re getting tripped up on a few items.
Regardless what ear era the vehicle is from, thinking you can sell the car for what you have spent fixing/upgrading/restoring it will always lead to frustration. Add in that your Duster isn’t the highly sought after 70-72 vintage and you’re even more underwater. Even selling a modern used car with brand new tires doesn’t mean you will be able to add $800 to the price to recoup the exact price of the new tires. It’s not a 1:1 ratio but something less.
Then there’s the narrower buyers pool for the 73 to 76 A bodies (compared to the 67 to 72 era) which puts you behind the 8 ball already. I suspect (and me owning a 75 Scamp has me in that narrower buyers pool mindset and I’m in Canada as well) buyers in that pool would prefer originality on those cars compared to modified ones that have components from earlier (8 3/4 rear end) and newer (crate engine) eras. Factor in your fibreglass fenders and bumpers and, aside from the sunroof, fender tag and VIN, there doesn’t appear to be much else from the 73 to 76 Duster on your car that the narrower buyers pool would be attracted to in the first place.
Finally, add in the work the new buyer would have to do to get it street legal (wipers) and running (tuning the engine), let alone having the charm/bits the 73/76 Duster came with from the factory, and its several thousand more $$ to get there after the purchase price.
Your Duster, as is, caters to an extremely small buyers pool which explains why you haven’t had many bites.