I think that you have a good start there. For that price you can afford to spend some money to fix up the cages.
If the wire is rusty, you can wire brush it, power wash it and when dry you can spray with "cold galvanizing" spray paint. We used it to clean up some cages with rust and it was a good product.
Spray paint won't fix wire that is rusted through, so check all the floors, especially the corners.
I've bought slantfront cages before from somebody getting out of the hobby. I liked them since rabbit rarely got out. The cages in the picture have the closely spaced floor wire turned up at the walls. This is an important feature that will help keep kits from escaping. This feature is often called "babysaver" and is worth having.
If you are going to stack, you will have to make some frames to hold them up. Don't put the top cage up too high or you will have to use a stepladder to reach the back of the cage, which is where the rabbits will want to go when you want them to come out.
You will also need some trays. If you don't want to deal with trays, get Bob Bennets "Raising Rabbits the Modern Way" or "Storey's guide to raising rabbits" by Bob Bennet. He shows how to make a slanted surface to direct urine and poop toward the back of the rabbit barn. If you can access the back of the cage stacks, this would work.
Have a good day!