I did own a body shop at one time and have helped a few people mount these NOS fenders. Any NOS fender on the market over the last 5 years is almost surely of the end of run batch. Compare the wheel opening lines to your rear quarters. They should be identical in dimension and crispness. If yours are rounded off then you've got the typcial NOS fender that's out there and they all sit proud at the feature line.

Yes, putting a bunch of shims in the bottom will pull the bottom of the fender below the rocker, but if you're running rocker chrome then it will be well hidden.

Do you have a good 3/16" gap along the bottom of your door? If not, raising the door up will help you keep your lines good top and bottom. Nonetheless, that extra metal needs to go somewhere and yes, a lot of force is needed to bring it in. The very center will always sit proud a little to allow the door to open into the fender, but the rest of the fender should line up nicely with the door.

I had to take a two pound hammer and piece of 2x6 to work mine in, but I was by myself. And I am not the only one that has ever had to do this with NOS fenders. If you have a helper, you might avoid this.

I have not heard of CDL, but can tell you that the feature lines on the Dynacorn fenders are much better than NOS. I also understand that Goodmark has come out with fenders made from new tooling that are supposed to be good.

I have NOS fenders on my car and am very happy with the gaps. An average 3/16" all around and everything is in the same plane too. This was after many hours of massaging and readjusting. They can be made to look good and if you run wheel well chrome, you can even hide the rounded features on the wheel opening to great degree.