Installing a single receptacle with an amp rating larger that the circuit supplying it is clearly permitted. How is installing a single 30 amp receptacle on a 20 amp circuit any different than installing ten 15 amp receptacles in a 15 amp circuit? Either way the circuit can be overloaded by the loads plugged in.
How do you connect a piece of portable equipment that requires a 70 amp circuit? A 100 amp device is the only option.
Curt
