After sitting 40-years, I suspect you are going to find a lot of seals that leak. The '48 truck sat 35-years and we just replaced every seal we saw....
Now I've got that song in my head "Bull in the woods, chewing tobacco; Bull in the woods, chewing tobacco..." I'll be hummin' it all day while I mow...
BB may want to swoop in and put a booth up selling either the plans for his design so the DIYers could build examples of his, or custom built rolling...