Hard to tell from the pics I found, where they end. For a hundred bucks, I can't see it going all the way up and in where you need it. You'll have to give them a call.
For that price though, you can get a good jump on some of that rust. You would just use the new panel to mark off the old panel carefully, sneaking up on it by leaving an inch extra or so until you can get it in the correct position to scribe your final cut.
Then comes the welding fun.
What kind of welder you got?