Nice job! I did the same to my 210 as well. I used a Dremel, a cheap set diamond-encrusted rotary burrs I bought off Amazon, digital vernier calipers for measuring the critical width of the slots, and a set of small files.
Here is one trick I did that another member shared with me that made installation of the fin moldings MUCH easier. I think it will only work with aftermarket fin moldings, because the top fin moldings need to be separate from the vertical fin moldings. That little bracket that normally gets screwed on to the rear of the fins, instead gets a pair of #10-32 or #10-24 x 1" long screws welded to them. You will need to drill the existing holes larger for the #10 screws to pass through. So, you would first install the top of fin moldings, then slide the little bracket into the rear fin molding, and bring it into position and engage the top part into the rear of the top of fin molding. Then from underneath, get the hex nuts, lock washers and flat washers onto those #10 screws, and tighten them up. That's it! Easy peasy!
Here is a solution for a problem I ran into. When snapping down the top fin moldings, some of the pins in the middle were not going all the way into the clips. The outer pins snapped into place, but not some of the middle pins. The reason was that the pin plate was flexing, and/or the new clips were quite tight. So, I purchased the longest needle nose pliers I could find on the internet. When I received the pliers, I ground the sides of them, so they were just narrow enough to fit inside the bottoms of the clips. From underneath, I reached up with the pliers and grabbed the bottoms of the pins, and pulled them through the rest of the way into the clip, until the ball end was past the bottom of the clip. Worked like a charm.