Yes, I am also interested about any info on S-250.
To improve the detection range of very low flying targets (cruise missiles), the plan was to elevate the SNR.
This concept was further improved with the S-300P mobile elevated masts (40V6).
Hpasp Free SAM Simulator, "Realistic to the Switch" (U-2 over Sverdlovsk, B-52's over Hanoi, F-4 Phantoms over the Sinai, F-16's and the F-117A Stealth bomber over the Balkans.) http://sites.google.com/site/samsimulator1972/home