[me and my metro]

It looks like the left rear lowered itself. Sorry I couldn’t resist. Most people will tell you not to cut factory springs. I have used cut factory springs for many years on many cars with good experiences. My current Saturn L200 has rear spring with one coil removed along with half the snubber. When you cut a factory spring the effective spring rate increases making it slightly stiffer. I actually put v-6 springs in place of the 4 cylinder springs to get a little more front travel. My car sits pretty level now instead of the factory rake.

I have seen and worked with the aftermarket coil over conversion stuff on a limited basis. The spring rate is up for stiffer ride but the springs are shorter so there is less travel available. This works well on the track or autocross course but can be brutal on the street. This type of coil over equipment also make ride height and chassis loading adjustable. It depends what your plans are for the car. Is it going to be a street car that you want lower to the ground or a race car that will be hammered on on the street?

I drive my car on the street and watch other people race their toys on the autocross courses. I have raced stock cars in the past and have several years of track chassis tuning experience.

Rust is a difficult thing to deal with once it gets to the structural parts of the chassis. Be thorough with diagnosis and cut it out to good metal then build it back. You may decide to find another donor body shell for your project.