Here is what I did with my 70 FB, I don't know if your 65 is just the same, I suspect it is. On the front fenders, I trimmed the width of the underside lip by about 1/2. You don't have to do the entire length of the fender lip, only about from the 10 to 2 position. Then you can work then over with a dolly and hammer or on a bag as mentioned. This is how the factory Boss 302 race cars were done. On the back I trimmed the underside lip to where the spot welds were. Again from the 10 o'clock to 2 o'clock position. I would not trim the back fender lips past the spot welds since these give a lot of strength to that area. You will find the process of 'rolling the lips' on the back fender will be more of a challenge because there are two thicknesses of metal unlike the fronts that are a single thickness.