hahahaha, there are always good sides with everything
i tried to get most of my metal smoothed out from inside before hand, 8 and 10mm round bar, with a bend in the end to help persuade the metal back to original position, but its helluva tough to do being a noob. Yours will be quite tough to remove as its on the main curve and its a compound curve too. so filler is what i would settle for. remember when you sand, never go lengthwise or vertical (front to rear or top to bottom). you want to go in an X (diagonal) motion or / and \. if you know what i mean? otherwise you will get flat spots from your sanding block. Oh, and always use a sanding block, even on final sanding. your fingers apply pressure in places that you dont want and can lead to "groves" where your pads on your fingertips have gone over....
but yeah, im sure you will do great and researched it a bit. Dont hate, but check this guys stuff out, learnt a lot from this oke, he is a bit irritating to watcha t times, but he is old school and know his sh!t, i mean, it worked for me:
http://www.youtube.com/user/diyautoschoolcheck out his techniques on the basic stuff, sanding, wet sanding, when to do what, how to do other stuff, filler etc etc...
like i said, he may irritate you, but just bear with him, you wont regret it.
The main thing is, dont rush. wait for the best conditions to spray, check precipitation and humidity. I have three weather sites open to forecast the weather before i even think of spraying hehehe..
oh, and temp is a huge factor, i have several weather forecast sites open days before monitoring the weather and humidity(55-63% is best). i like spraying at 24-26 deg Celsius. I do this because they spray Mercedes Benz's at work under these conditions. Except they have huge dehumidifiers and and and to control their temps and humidity.