There are several ways to lower this car, some harder than others and 1/2" up front is not likley to make enough difference in geometry to matter though it will transfer a bit more weight forward which is not usually a good thing in a front heavy car but then again, probably not enough to matter.
A little background: I have been modding cars for 46 years, Datsun 510's, AWD, FWD, RWD, BMW, Vettes, etc......so fairly well experienced in this and in all out competition alignments, etc......though just for me I have a well equipped shop including digital alignment gear, scales, lift, tubing bender for cages, etc........
1) Modify the struts and keep the springs stock.
A) Spring perch lowering, most difficult as shocks have to be either kept in ice water or taken apart for rewelding
B) Top hat modification, depends on design as to how complex or if possible
C) Modify mount location to knuckle, on the strut itself, from a quick look this would be rather simple, for me at least.
2) Modify the springs.
A) Cut just enough from the top or bottom to reach desired height. This is dependent on the design of the spring top or bottom and where it fits the perch or top hats. Looks like the bottom might work though a smaller diameter coil at the end which could require modifying the perch so the wider coil fits properly. I would have to take the struts off to see what could be done at the top hat location. This will stiffen the spring a bit, how much is hard to determine.
B) Heat springs until desired drop is achieved then have them retempered.
C) Have custom springs wound.
3) Modify the knuckles.
A) See if any other knuckle would fit and accomplish the goal, not likely but never know until you look into it.
B) Modify the knuckles, not recommended unless the absolute last resort and it must be done then it better be done by a very competent person.
I have done most of the above with complete success starting back in 1972 or so and won many autocrosses, some ralleys, etc....
Hope this helps

Rick