I had a look at that part number and yeah, there is a Bendix version which might be available in Australia.
The dimension of said rotor is close to the Focus mk1 rear rotor, at worst you'll need to shift the offset of the mount bracket or cut new ones.
To help out there's a protex site which has measurements of nearly every rotor known in the universe, just type the dia and hat height, the stud pattern doesn't matter as can be drilled to Escort. But I'd sway to using focus ones as are cheap and common. I have a spare set from my focus which will go on the Escort mk1 once my calipers arrive.
Your calipers are to bran new to be old Sierra ones, I'm sure Sierra calipers got a follow on gig on mk1 focus or are slightly upgraded, pads will tell you by part number.

Handbrake cable, I used Mazda 323 once on a conversion, virtually perfect length and all

Good idea - I'll check the pad part number I have those, yeah i've been looking and Focus looks close, would just need a shim made up to sit between the mount and the caliper.

The only uncertainty is the diameter clearance, I'll have a look at that site you mentioned!

Mk5 Escort Cosworth 4x4 rear pads .... hmmmmm
 

91 escort, yike.. that'll be annoying to source pads. Seems Focus mk1 or mk2 calipers look a better option.
You've got the setup now may as well carry on with it.
Cross reference this with the 90s fiesta etc

RDA7933 Fits Ford Focus R/Rotor

Specifications:

Diameter: 252.5mm
Height: 33mm
Centerhole: 63.5mm
Thickness: 10.4mm
Minimum Thickness: 8.9mm
PCD: 108
No. Holes: 4
Type: SOLID

Well that was a mission but that Protex website came in clutch, found a rotor that will fit - from a 2000 model Ford KA.



 
Now I just need to find a bloody stockist - the only difference is that the actual rotor is 2mm thicker - shouldn't be an issue and if it is i can clearance the mount.

Good thing we have the Ford Kak until 2003ish . A wider rotor shouldn't be a problem with floating calipers as long as it spreads wide enough

I've bought from Auto superstore before for Mrs cars.:
https://automotivesuperstore.com.au/protex-sdr529 $136 pair, just need to wait for stock.

Ok we got discs! 

I dropped down to the local brake place with my handbrake cable this morning, while I was there I asked if they could get the KA discs and I was floored that they would have them by this afternoon . 

Then I made a tactical error that my arms are now paying for... I offered the discs up and saw how little material needed to come off the axle hub to have them fit... so I decided to give it a crack with some emery cloth to get the discs on instead of removing the axles to take them to get turned down...  

Long story short the passenger side is 90% done.. It still needs a tiny bit more to rotate on the hub freely. Pure stubbornness on my part was the only thing that got this done - it took almost an hour of filing and sanding to get it all the way home on the hub...
 

 
So that revealed the next issue, the caliper needs a spacer, it's about 5mm off. 
 

 

 
That washer is just under 2mm thick, so A 5mm spacer should get the job done. I've ordered some aluminum ones off ebay that should arrive early next week, in the meantime I have more sanding to do....

I'm so glad I have a lathe!!
You don't have a die grinder burr to speed up the job .
5mm, could you use a piece of strap and drill holes? A good idea is to sika the spacers on the mount so your not fiddling about trying to line everyone up to bolt together.

My rear calipers are late to arrive, should be (ha) tomorrow or Fri ..

I hope you have an easier time of it, these have been painful, managed to get them sitting right with a bit of work with the file and two 3mm washers, I might actually tack them on to the caliper mount cause I have to repaint it anyhow, it got scratched to all crap.