Sorry, I don't have one. But are you sure you current ECU is dead ?
Maybe you should start there before you throw new parts at it, especially if money is tight.
Did you check the connections ? Any trace of damage or corrosion on the board or plugs ?
What are the symptoms ?
I think you should post in the technical forums first, lots of knowledgeable people there who might be able to help you.
Put your location in your profile, it can help find local people with the right tools or parts to swap.
There's some info here about the motronic interface :
Information on the Porsche 964 OBD Motronic interface
The following page shows you how to read check engine codes without a tool (US cars only) :
Durametric Software - How to read fault codes on Porsche 964
It could tell you if the ECU is at least alive or not.
Good luck with your project.