I want to do the same thing. I have looked at several other heads, but so far I haven't found anything close. I will get to the local salvage this week yard and see if I can find one to measure. I will let you know.
Your chances are slim to none. Bore spacing must be exactly the same, bolt holes need to line up, water jackets, oil passages, oil drain, and the critical timing gears/chain must line up exactly or it will wear severely. Knowing the Saturn is far more undersquare than the Opel (small bore/long stroke), the bore spacing is likely off by a lot.
Why not put the complete Saturn SC2 engine in? I'm not much for engine swaps, but at least the Saturn is a GM engine, all aluminum, and does have reasonable hp (123). And it's even a 1.9 litre, for what that's worth. I had actually contemplated doing this swap to my father's GT years ago, until I came to my senses...
Actuly why not transplant a Saturn SL motor instead of the SC? The SL series motors are Opel motors. But the problem is all the SL Saturns are front wheel drive, so I'm not sure about matching a rear wheel trans.