Sounds like you need to order a custom Dexter
axle. Many local shops can custom order these for you. In my Baja Burrito Resto thread I have a quote and some details on Dexter. You get into issues like trailing/leading axle, getting the right angle and maybe a change in wheel size. This and other things to consider.
Not sure why you would need the e-brakes? This will limit your options and make the cost go up.
I chose to switch mine over to a leaf spring, which I did get from e-trailer. Again, how I did this was in my post.
If you are in the business of replacing the entire axle ... no matter your choice, I would consider beefing up the frame at least where the axle sits. This frames are really thin and are prone to failure. Using some pieces of angle on the frame would really help distribute the point loads of the axle on the frame.
Good luck. Feel free to PM if you have particular issues you want to discuss. My resto is on hold at the moment so I don't check this site that often.