What width are you trying to achieve - backing plate mounting face to backing plate mounting face?
I don't know of anybody who can supply narrowed tapered axles (and I wouldn't invest in them anyway!).
Another approach would be to get rid of the tapered axles/hubs from the early Ford rear, weld on new modern bearing ends on the rear-end housing bells and run modern 28 spline 8-inch axles and later drum brakes.
The ring-gear needs to be bored to except the later side gears and the differential housing needs modified as well.
You can get modern axles in any width you want - with 5 1/2 x 5 bolt circles as well.
Also, this type of rear will be a LOT stronger than any V8 rear end with stock-style tapered axles (the ends). Talk to the new owners of HotRod works, they can supply you with the modified side-gears, can modify the ring gear and differential for the slide-in-axle side gears, etc.. They can also build you a complete rear end.
An important note is that to weld on new axle bearing ends, you need a big-ole alignment bar and 2 sets of "pucks" to pick up the outer bearing IDs and the two differential bearing locations. This is so the resulting bearing bores and differential bearings are all running on the same centerline - you shouldn't just weld the ends on and assume you can get them correctly oriented.
https://hotrodworks.com/
Note: You'll also be using later Ford drum brakes - which is an added bonus in my mind (lots cheaper than repop early Ford brakes).