Another Dutch member, cool!
I am located near Utrecht, so unfortunately 200 kilometers away.
DAF 55 are funny vehicles, I suppose you remained the CVT gearbox ? Because that is the party trick of the DAF, being able to accelerate very well because the engine gets a fixed RPM. Also: because there are 2 CVTs the car has essentially a locked differential making it easy to slide around in. A colleague of mine owns a DAF 55 as well, but he still has the stock carburated 1100cc engine in it. Can you post some pictures of the project ?
If I am not mistaken this engine is a Renault Cléon based engine. Renault used this engine till around the year 2000 in the Twingo. I think the easiest route would be to use as many Twingo parts for the EFI system. There will be plenty of 1990-2000 era Twingos available at the scrapyard, we used to have one but it rusted away from us. Mechanically it was still doing well. Not sure what parts will be bolt-on though... I am also not sure what EFI these Renaults use, it might be that they were running single point injection. How do the intake ports look? Are they siamesed ?
Parts you will need specific for your engine: an intake manifold with throttle body, injectors w/ fuel rail, trigger wheel with sensor
Parts which can be robbed from many cars: ignition coils/coilpack, electric fuel pump, MAP sensor, air temperature sensor, coolant temperature sensor, idle control valve, throttle position sensor
I would also suggest to buy a wideband O2 sensor for tuning.
If you need help in Dutch you can reach me by Skype if you want to
but possible to see on FB after a search 'daf trionic'