Wow what a great documentation of this project! Nice job!
If it were me I would have the foundation buy you a cutting torch set. Northern Tool sells them for $129.00.
They don't come with tanks but they can be found on Craig's list pretty cheap.
You are doing them a huge favor, why should all the fuel and tool costs be put on you?
That is a lot of labor and expense on your part, a torch set would make life easy for you!
Good luck and again a fine job!