Delta winged aircraft such as the Dassault Mirage III have an approach speed of 170 knots as specified by the manufacturer.
The Mirage F1 was designed to have a lower take off and landing speed than the Mirage III, what would it have taken to reduce the Mirage III landing speed to 135 knots by increasing wing area and reducing wing loading, and installing the F1 engine, and adding leading edge extensions (without adding canards)?
Could this be done by reducing maximum speed to say Mach 1.4 instead of Mach 2 without sacrificing climb performance?
Some figures: Mirage III Thrust: 60.8 kN Rate of climb: 83 m/s (16,300 ft/min) Wing Loading:274 kg / sq m
Mirage F1 Thrust: 70.6 kN Rate of climb: 243 m/s (47,835 ft/min) at high altitude
There is a formula relating change in stall speed to weight of aircraft, not sure if it is applicable here.