First off, NO the parts were NOT poorly fitted.
Ford did not want people wasting time on the floor fitting parts. It cost time and money. So most of the production part were much more precision fit then you might think.
When fitting fenders you first fit the light bar to the braces. I spent a few hours adjusting the light bar and braces until the bolts just fit in easy. Yes, there is a magic spot where they just fit together and until you hit it the bolts do not go in well. I cold bent the light bar in a vice by hand. The braces I did cold with a short piece of pipe that would go over the brace and let me put in a long metal lever.
Once you have the braces correct for the light bar you now fit the fender. The fender is fit to the frame edge and then you have to figure out how to reshape the fender to fit the light bar postion. Again a lot of change, fit and step back to see the 2 fenders are even. If the bead line has been welded then all bets are off on getting anything to fit. You will have to cut the bead line and make it all work. Just a small change in the bead line will make the whole fender shape wrong.
Ultimately the bead should be straight and vertical from the bolt to the bolt and along the running board. So you also have to align the running board brackets. It is a system that has to fit together.
Keep in mind I am doing a 31 body.
Later I bought a pair of NOS fender brackets. I made a jig from them to see how close the brackets I adjusted on the car to the light bar came to factory. They were dead one, well one side the bead was off a bit, but that I knew because the fender had be worked by someone else off the frame and some curves were messed up. Off the car you would have paid premium price for clean rust free fenders. Both had been accident victims but no bead cracks and both had been kinked. I found this out when I sand blasted them.
While all the above seem complicated. It took me some time to figure it out, but in the end it was not very hard to do.