The technique for removing a row of spot welds is one I've used for some time having tried numerous different ways, breaking it down into individual little sections allows for the spot welds to be removed with absolutely minimal risk of damage to the remaining flange, unlike when using an air chisel or a hammer and chisel, the pieces twist off very easily and without distorting the flange.
The old sill was generally in good order, the rot was restricted pretty much to within a few inches of the lower seam as Frank suggests.
I did consider leaving most of the original on the car and cutting what I needed from the new sill but that means you have a joint to tidy up, using it all up to the door seal means your welding is on the flange that's then covered by the seal and you get a nice fresh door step.
The other issue was a hole in the top edge about where the front corner of the door sits.
With the new sills it pays to balance out how much of the panel you use and how much original car you leave on, nothing in the rules says you have to use the whole sill. I cut a good couple of inches off where it goes behind the front wing as it keeps the joint lower down away from the door hinge and it being completely rot free there was no point in going higher, a joint was needed wherever it may be so just make it where best suits.
I have kept the main section of removed sill so it can be given to the paint suppliers to get a colour match as there are a few shades of the blue available, even though I'll be spraying the whole car and probably the engine bay too I'll try and match the correct shade. I'll take a snap of the inner side of the panel next time if needed.
