using a 300tdi EDC engine as a donor for conversion?

I'm wanting to make my RRC a 300tdi auto, as I understand it the 300tdi auto's all had EDC, so I was wondering what would be involved in making the EDC work? How much wiring does it need? I dont really want to have to buy a 300tdi auto donor engine and gearbox, and a mechanical pump and a rake of other bits as this would start getting very expensive very quickly.

So What I'm hoping is that the ECU is on the pump and the only external wiring required would be a throttle position sensor. But I accept thats likely to be wildly over optimistic so I'm looking for any insight from anyone who has transplanted the EDC system and how to do it. Or is there a shortcut to jury rig the EDC pump to run sans ecu?

Early 300tdi autos were not EDC, but they were numb beasts, hence the move to EDC.
If you do use an EDC engine, you will need the matching "fly by wire" accelerator pedal and I think the ECU also takes a signal from the electronic speedo sensor.
Lots of people convert EDC engines to a manual pump when they retro-fit them to 90/110's, but you also need to sort kickdown linkages if you are keeping the auto-box.

I know you list you don't want to do this, but a working if rotten / wretched auto disco 1 can be had for 500 quid and under, & the best solution is simply transplant a factory setup in, ECU included. Trying to cobble together a setup from ebay spares is never easy and will be more expensive without fail, and you'll have a wiring diagram in front of you with a complete car, which you can see if actually works before hundreds of hours of work. You didn't say what engine you have (ready transplanted 300 in there already for example?), if there is one, or if there is a box or anything already in the shed so I've assumed no.

Secondly if you fancy an arse ache you can make one of the early bosch EDC VE pumps work without an ecu (no it's not part of the pump), the early EDC VE's need at minimum, a signal from the accelerator pedal (TPS), a signal for the fuel rack position sensor input (FRPS), and a manifold absolute pressure (MAP) sensor input signal (not actually necessary to make the engine fire). The stop / ignition solenoid on the pump needs to be wired on and any immobilizers bypassed if there is one.

I'm not 100% certain as i've no experience of the auto landies, but as far as im aware they had no MAF or crank position sensor, only the minimums I listed along with - coolant temperature sensor (for various map features), engine speed (I'd assume this is calculated from the alternator pulse), boost pressure, Edit - Needle lift position sensor (injector with the wire in it, also not necessary to run the pump) road speed (?), and brake pedal sensor (?). both the (?) I'm unsure of but generally are on automatics for the gearbox logic in the map.

This will produce a somewhat limited driving experience but if you merely want to get going for very limited funds it is do-able (if you already have an edc 300 kicking about, if you have to actually buy one this is all a bit moot). There's a few blokes on youtube who've got some of the more complicated later VE and even VP pumps going with a full map on an arduino, which is very nifty! Most of them and even more recent CR engines can be mapped with aftermarket ECU's, mind.

You will need at least a basic understanding of electronics to make it work of course, and then a bit of time spent adjusting the system to end up with something usable, nothing you cant pickup from google if you're inclined. Not having a functional engine to steal base sensor values off is a real problem though unless you have a friendly mate who doesn't mind you poking about with his loom, as i'm guessing this isn't common knowledge, i've lifted this experience from bodging my old 525TDS,

edit - also had a look in my old notes I think, don't quote - that the TPS feeds straight to the pump, and then back to the ecu - so not a signal range to worry about as long as you get the correct pedal box, and I've written down the FRPS signal to the ECU was 1kohms and under (assuming at 12 volts but might not be), in that I started there with a variable pot and turned it down til it was right, so it is likely the feed signal back to the FPRS is in the same range.