Every so often, having the correct tool for the job makes life so much easier.
The otherwise excellent instructions from High Level for their Coffee Pot kit refer to using a piece of wood to bend the inner of the saddle tank squarely up. Or you can do as I did and use a Hold-And-Fold tool.
Very easy, very accurate, and you should get perfect straight bends. It's one of those "investment tools" that you don't use every day, but when you do, you reflect on just how easy it makes things...