Ian,
With R2 = 200000 ohms the signal at the R1-R2-R3-D1-D2 junction will be 1/6 of the input votage. For a maximum input of 35 V the voltage at the input to the op amp will be less than 6 V. As you suggest D1, D2, and R3 provide additional input protection. The maximum voltage drop across R3 is the forward voltage drop of one of the diodes, typically about 0.6 V for silicon diodes. That means a maximum of 60 uA into the input pins of the op amp. In reality it will probably be less because the forward drop of the internal protection diode in the op amp also is part of the circuit.
The TI data sheet for the TL074 does not specify its behavior if the output is driven to maximum, although it does claim the device to be latch-up free. If you care about what happens in the first 10-20 us after coming out of an overdrive condition, you will need to run tests. So not rely on a simulation for that because most simulation models do not handle the out of range conditions accurately.
Lynn
