Hi Nicolas.
Where do you live in Belgium? I'm not far from Marche en Famenne.
I'm building also a modest 1585cc. With a w110 ( I think I should put another grind for what I plan to do with it as a vz14 or a w100).
Carbs are kadron, heads are from LoÎc Charpentier. 043, stainless steel valve, bugpack spring etc.
I'm planning to enlarge venturis to 30mm max. According to what I've read, it is a good combo. I will first test with stock venturis and jet to see how it runs.
You can use this calculator, if you don't know it.
http://www.flat4ever.com/?page=carbusIf you are with single springs (reinforced), max rev will be 5.500t.
A friend run a 1600cc with 40idf and change to 36 drla with 30 venturis. I will tell you how it runs.