Lets take the Cold War Stealth plane, and assume that its RCS is around a tennis ball.
(size of the plane is similar to an F-4 Phantom, so it is a great engineering achievement)

What do we have (using metric target acquisition radar), to shoot it down?

SA-75M Dvina (SA-2F) with the metric P-12 (Spoon Rest-A) target acquisition radar.
Metric P-12 could detect the Stealth at the maximum of ~25km.
RSNA-75M (Fan Song-F) centimeter band fire control radar could detect it at maximum ~10km.
Minimum effective range of the V-750VMK (Guideline Mod.1) missile is 5km.
During the '80s when the Stealth was active, Dvina was generally replaced by the Volhov system.

S-75M Volhov (SA-2E) with the metric P-18 (Spoon Rest-D) target acquisition radar.
Metric P-18 could detect the Stealth at the maximum of ~30km.
RSN-75V (Fan Song-E) centimeter band fire control radar could detect it at maximum ~13km.
Minimum effective range of the V-759 (Guideline Mod.5) missile is 7km.

The Neva (SA-3B), KRUG (SA-4B), KUB (SA-6A), Osa (SA-8B) has no metric target acquisition radar, and the P-14 (Tall King) of the Vega (SA-5B) can be easily annihilated with a Tomahawk before any conflict.

Of course, if you mix the Neva (Low Blow) fire control radar with the P-18 (Spoon Rest-D) target acquisition radar, than nasty surprise can happen...