These cars were very light back in the day . The 20 and 22 inch wheels were common, this gives you good ground clearance. They were geared a bit like a farm truck , and they were built to be able to twist and move when they were drove.
I think Harry is spot on. They will never go away because the traditional rod movement is so big. The kids are into this type of car because they do not have a fat wallet for the billet special.
Good luck. I would think you would like to start with clear square stock. you can polish it when you get it done.
Start with the top and sides of the bottle (all the way to polish)and then work on the bottom after you cut it off.