Assuming that's not some electric motor transplant and you have the 150bhp Twin Spark petrol engine, then yes the throttle body itself is part number 60657874.
However the throttle body is just a throttle body... usually alloy, maybe plastic... with an air regulator flap in it which opens when you prod the accelerator and closes on a spring... so not much on there that can go wrong.
It's more likely to be the BBoB on top... aka Injection Control Unit.. since that's got electronics in it. I dunno if you get one with a new throttle body assembly
but you can also get the ICU separately - Art. 46768472.
The bad news is it's not much cheaper on its own than with the throttle body (assuming the assembly comes with a new ICU)... but you can get "reconditioned" ones for 1/2 - 2/3 the price of a new one - Art.71721936
The problem could also be the Throttle Position Sensor which again is "part of the Throttle body assembly" but is also available separately - - Art. 71713829
The beast sounds like a CF2 engine based on your TB part number.. and "any" TB off a CF2 engine will fit. The only odd-ness I see is that the ICU is different from a 145 or 156 CF2 engine, even though the TPS is the same.
If you can find a complete second hand throttle body with ICU and TPS from a GTV or Spider, then that will fit straight in. The 145/6 or '56's look like they can only provide the throttle body itself.. although your GTV ICU and TPS will fit on it.. (but see above re. TPS being the problem).
155 and 166 didn't have this motor... and the bits are tooo different.