Re dual drive.
On uk ebay, good used dual drive hubs, usually 8 speed, come up frequently for less than £100. You should be able to get dual drive finished on your birdie for less than £200 even if you get someone to build the wheel up. You might even be lucky and find a disc brake version.
You can sell the old rear birdie wheel, (pm me), or keep for spares or to utilise a different tyre set up.