Most production cars had pressed steel fuel tanks so I wouldn't worry about it. I think 4 baffles is too many though. Just make sure its protected from corrosion with plenty of nice paint etc
I wouldn't make the tank too small, or you'll have an awful range on the car. I've made my tank slightly taller, but sitting in the same location. I imagine if you fit it on top of the diff cage, any kind of servicing is going to be a nightmare, unless you wanna drain and remove the tank to adjust the handbrake cable
