The FRED supposedly ran out of pitch authority before it could reach a true 1G stall, but quoted speeds are prone to all sorts of potential errors:
Was the pitot static system calibrated? static errors especially can yield large errors at low airspeeds.
Was the measurement made at zero thrust? - Idle settings can vary considerably.
Lift can also be generated from the fuselage and tailplane, though it's hard to imagine the Fred is particularly effective in that respect.
Aerofoil data generally applies to a semi-infinite wing as the wind tunnel set-up tries to avoid span-wise flow and end effects.
So there are a lot of real world effects that need to be considered in calculating stall speeds.
VGs should reduce stall speeds by keeping the flow attached at high Alpha thus increasing Cl(Max) but their effect varies considerably between different aerofoils.