Hopefully this will clear some things up.
Eibach springs are only available in the 2804's... aka the Shadow high rate package.
I purchased and installed Koni's and Eibach's on my 88 Shelby Z last summer.
My ride height was to be honest.. wasn't much if any different. However, My struts/shocks were completely beat so that MAY have had something to do with it.
Also, GR2's are not to be used with Eibach. Not saying they are bad, just not up handling the spring rates.
KYB Gas-Adjust rear shocks are a very good alternative to Koni's. With no concrete evidence, I do believe they are about equal, having owned and used both.
I've yet to find an alternative to Koni Struts, Beilstein is not the answer. They aren't even as stiff as the koni's on medium setting imo. I also could not recommend blowing money on Beilsteins. Although I don't know what brand to recommened, I'm sure you could fine some struts just as good at a local store. The cheap non-branded Monroe come to mind as Beilstein class.
Hope this helps.