D5254T (to 2002, Audi) What gearbox for rwd and how simple can it be made?

[warninglight]

I'm mulling over a project idea in my head at the moment, as to how I might fit a Torquey, old school, veg friendly and characterful diesel into a much older vehicle.

I've always liked the AEL engine Volvo used in the 850 diesels, and I have a good one currently.

If I was to build it for an older vehicle, does anyone have experience of mating up other gearboxes (740 diesel manual, an inline VAG one?) And perhaps cable controlled injection pump conversion, doing away with EGR etc.

Could it even be run without an ECU? Or might it be easier to fab up a pedal box to take an original throttle position sensor, keep the MAF etc on it all feeding in to the ECU?

The donor would likely be a 1997 V70 manual.

Nobody seems to have done anything like this that I can find, I guess the D24T is an easier simple option and for performance T5s are common swaps. That only adds to me wanting to do it with the 5 pot diesel...