If your SS Nova is an SS because it was a BBC (all BBC motors were only available with the SS option) it should be pretty conclusive as:
Big block came with multi leaf rear springs, multi leaf rear springs perches on the numbers matching 12 bolt rear, a TH400 tranny or Muncie 4 speed if manual, cross member for tranny is offset 1" to the passenger side, has BBC frame pedestals which raise motor on drivers side and shift it one inch over to the passenger side, a four core 23" wide Harrison radiator, the shroud for the fan is offset one inch and thinner than the A/C version of the SBC shroud, 63 amp alt, 3/8" ID fuel line, BBC heater core box with correct cover (water lines exit in middle not on end with no "extra holes" in the cover, BBC front springs (heavier gauge wire than SBC spring), front sway is notched to clear damper if so equipped and is 1-1/8" diameter, Z-bar for the clutch is three quarters of an inch longer than the SBC unit, and the arms are clocked differently than the SBC unit, it with have an 11" pressure plate and clutch with a 164 tooth flywheel, high torque starter motor (has the front winding 5/8" further forward of the solenoid requiring a brass spacer) with offset mounting bolts, 2-1/4" dual exhaust with resonators.
If it was a 350 things get murky because basically the only difference for the SS besides pot metal trim that can all be bought on line was a 14x7" Rally Wheel rim, HD Delco shocks (odds of still being installed today are slim) HD 2" wide rear brakes on the date code numbers matching 12 bolt rear end (disc brakes were standard after '69, but not all were powered, and even an SS option didn't require it), Sway bars on the front and rear (often removed by owners interested only in driving in straight lines), three core radiator (23" only on A/C models), Gauge Package consisting of oil, amps, temp, and tach (console was optional, not part of SS package), and SS on steering wheel or dash depending upon interior trim level (most who buy the chrome badges often overlook the interior).
If it has all of this and no documentation enjoy it but I wouldn't recommend claiming it is a "true" SS as someone some where will argue with you. My advise is enjoy it, and drive it like you stole it.
Bid Dave