Chads right. No SB SS's in 70. You had two choices. The RPO Z25, SS-396, and the RPO Z15, SS-454.
Big-blocks came standard with a 12-bolt rear axle.
The rear anti-sway bar (F41 suspension) was included in the SS package on all Chevelles starting in '70.
If it doesn't have these things then its NOT an SS.