While people are looking at adjustable dampers etc.... I've just bought some adjustable top mounts from MC Motorsport for my V6 X1/9. They are £150 a pair from his web site, £160 a pair from his eBay shop (?!). The top mounts are intended for Ford Escorts, but I noticed they are pretty damn close to the same PCD as Beta top mounts, within a millimetre or so. With a very tiny bit of fettling of the bolt holes in the strut tower these would fit. They won't give all the adjustment available as the clamp bolt heads will touch the edge of the hole in the tower. Tomorrow I'll offer one up and take some pics. Clamp bolts and threaded holes are all M8.
No mods to the existing holes needed. The main plate may need its top edge chamfering a little to accommodate the curve of the strut tower, when I offered it up it seemed to foul the inner side of the tower but this may have been just the thickness of the underseal; when I tightened the four bolts it seemed to come up pretty snug.
The adjustment is about 12 mm each way. With a small mod to the sliding part, i.e. having three tapped holes each side instead of two, the full adjustment range could be obtained.
Something else I'm thinking about...