Thats @djvu205 - good advice.Gti struts have a drop link tab welded to the strut tube and si ones don't. Si has no front sway bar (it has radius rods) gti does. Also I think gti struts are marginally longer than si (approx 15mm)
basically if your keeping the original si front end use non gti struts. If your going firmer suspension and/or a gti front end later you can probley buy gti struts and run in si frontend but the drop link tab fouls on the si brake hose mount that's on the body. I modified my si brake hose mounts by moving them when I fitted the gti front end. That way I could use 205 si 205 gti or 306 struts. 306 struts put the drop links in a slightly twisted position due to the position of the tab on the strut but they still worked fine for me. The reason I used 306 struts was because they came from a xu10j4 car that had only done 60000km.
I plan to put firmer front-end suspension in (fix the problem the first time) and when opportunity (and parts) appear upgrade it to a GTI front end.
Sounds like the best approach is as you suggest - move the brake line mounts up out of the day and install GTI springs and dampers now.
Thanks,
Sean