Wow. Too bad about the rust. Those tanks are not easy to find in good condition, and finding the fenders and side covers that would match makes it really hard (front fenders can be tough to find in any condition.) If you love these bikes, the best bet would be to repaint them. You can restore the tanks you have there if they are not rusted through. The thing you need to decide is how far to go. A total restoration can run several thousand bucks, but if you are just wanting riders, you might be able to keep it reasonable with some new cables, wheel rims, spokes, tires, and seats. SL70's are a great mini that an adult can ride. They are collectable, but restoring one is usually a break-even deal at best. If you decide to restore, repair, or sell them, there are a lot of people on this site that can help. Check out this SL70 thread:
https://www.planetminis.com/threads/sl70-freakout-show-your-honda-sl70.172968/