I take it IS42 is the naming of the headset size (quick good search)
I popped mine apart and all the races are not really there on the bottom one and 3 bearing dints in the top one so useless.
Now it has the dimensions on the side of them (both different) 45/45 ACB and the inner outer measurments
But I've lost the bit of paper I wrote it one
I think one was 41x30.15 and they are both 7mm thick
No idea what campag pattern means, but assume it's the 45/45 bit.
( I now need both after having a look at them)
Probably just get the same headset as it'll be cheaper