As chance would have it, I haven't logged on in at least a couple years but I did this morning and saw that someone is converting a 122 to Demonic-tronic. I used to have a 122 (sedan) I did the same thing with. I have dealt with the same issues you've described in your posts and sort of remember the solutions.

For fuel delivery:
- The D-jet fuel pump is good at pushing fuel but bad at sucking it. Make sure to mount the pump as low as possible to minimize the force it must overcome. If you unplug the leads from the starter (but leave them connected to each other) and turn the key to ignition do you hear the pump run continually? It should, but it gets the queue to do so from the same power that makes the starter solonoid engage.
- The pentagonal Waso cap is vented.

Fuel return:
- I did a similar thing to you I had very poor luck with the tee fitting described in Cams vclassics article. The hotter it got the worse things became. The proper return solved this.

Was there anything else you are having issues with? I never wrote the whole thing up but the photos I took when I sold the car are at: http://www.pbase.com/nitropiggy/122_auction. When I write my memoir I'll include a chapter about the conversion.