Hi,
Take a look at my build.....done the same to a 84 cabby.... www.escort-cabrio.nl
The site is in Dutch. Go to Galery, google translate will help you

I used the S2 tank. I machined an adapter from aluminium. The S2 fuelgauge sensor is the same risistor range as the MK3.
Make sure u use the vented tank cap, or use the tank vent pipes as on the S2.


S2 fuel cradle: just drill a hole in the Sparewheel plug, and make a bracket with nut welded to it on the existing hole between rear track arms:


Fuel pipes:
You MUST need the underbody fuel pipes from a MK3 injection, S2 won't fit! (xr3i, RSi, S1, 1.6i)
You have to make a new flex fuel line from pump to metal underbody line (S1 has accumulator near tank, S2 has it in engine bay)

I hope this helps,
Good luck!
Sven