Suzi-Rotary? I had one once, spent $100 on a new battery, $60 or so for the manual, got it to run some by kick starting till my leg was hurtin' bad. Never got it right, started on the 4 cable carb to set-up, got dissappointed real fast, sold it and parts bike to another "dreamer". It even had the early odd dash and stuff. I made the changes listed in manual to one points set and some other stuff. Never did get to ride it.
Anyway, back to patches. I understand you should just cut enough orig metal to get to clean and cut patch to match. On the flanger, I've wanted one, but most guys say that just makes another seam for rust to start at. If you butt joint, Harbor Freight and Eastwood have these little butt joint clamps to align metal with a small crack for welding and allows you to take out later. Also, they have "Clecos" used in rivet like holes to temp hold the metal if overlapped. They are neato. Need the pliers to put them in. Aviation fellas use those. Inner panels I've seen dont look like much, you should be able to make something there. If you dont, the new corner becomes a "scoop" for cold air in winter, I KNOW!
On that nibbler, those darn little bits get stuck in your shoes and clothes and go all-over! They do work for tight/clean spots though. I usually cut over a garbage can if loose peice. I'm thinking one of those Sawzall looking Air body saws is the better answer for cutting out old metal.
There's an article in Truck Builder I have about doing cab corners. On a **** of course, the most worked on trucks in these darn mags it seems. Good pix and steps shown. Hard to find magazine as it's new. Might be last issue, not sure.
Good luck, at least your OUT THERE and working on it, not just sitten' round hating the cold like me!
:p
