Erik Reese inquired "...Looking for any 3 or 4 speed English threaded freewheels..."
Older Regina five or six speed freewheels (Extra, G.S. Corse etc models) are cost-effective four speed freewheels. Remove the fifth cog (counting up from the spokes). That cog threads into its neighbor 4th cog and does not thread onto the freewheel body, so its removal leaves you with a four speed freewheel. You can assemble a custom freewheel by purchasing a number of such freewheels (which can be inexpensive on eBay if you bide your time), and swapping cogs around. English threaded Regina freewheels are identified by 'FI' scratched on their back facing the spokes, or a single circular groove there.
Peter Brueggeman
La Jolla California USA
4peebee(at)peterbrueggeman.com