Pete,
I use a 4 1/2" angle grinder with whiz wheel for the big cuts. I use a small air powered 2 1/2" whiz wheel for the small cuts. And a body saw for some cuts if the other two won't fit. Don't be too worried if your cut goes a little to far in the corners, you can easily weld those slices up. And if you need to make rounded corners you can use a drill and bit with the radius you want then connect the 4 corner holes with one of the 3 cutting tools I mentioned. Here's a pic of the main cutting tools I use. And in the other pic you can see where I had to slice a little further than I wanted. But that was easily filled with weld.
Give it try. Nothing to lose. It's just metal, you can always put more in if you mess up a cut. But have yourself a cheap metal brake, set of body hammers and dollies. Also a decent welder. Most of the small hand tools you can get from harbor freight. Biggest investment will be a welder but you can get a decent 110volt welder for panels. Here's some of my stuff. Let me know if you have any questions and don't be afraid to cut some stuff up!::thumb::
Thanks Ray. I do seal up the rust with a type of rust encapsulator. I did the inside of the door and inner door seam with it. I just brush it on. I don't know what it is or the name of it. My buddy works on boilers and steam pipes and hooked me up with it. It seems to work pretty well. You brush it on and it's white. When it comes in contact with rust it turns purple. I used it on the frame of my truck few years ago and my doors. They are still holding up well.
