Paul's got a point here! Better to put the brake fluid reservoir in the same position as it was on the Sierra, and not horizontally as I did. I don't know why I haven't thought of that when I did my support! But I think it is not such a big deal.
Regarding the hose, the problem is that the nipples on the Sierra reservoir are 12mm OD. And it is very hard to find brake fluid resistant hose bigger than 10mm ID. I'm using 10mm ID hose, that I could force on the 12mm nipples of the reservoir, secured with clamp, it is OK. Then I have plastic (Delrin, which is brake fluid resistant) reducing hose connectors 10 to 12mm on the master cylinder inlets. All secured with clamps. But if you can machine your own hose joiners in aly, it is even better!
Perhaps other reservoirs like the one from Fiat Punt Paul is talking about are more suitable, as they were originally remote. Rally Design has one which has 8mm OD outlets, but it is of course more expensive than a second hand OEM one.