Yeah, jeez - so - a-LOT going on here...

Um - I was there once too...

Don't worry about it!
So, the 24 valve heads don't bolt to the 12 valve blocks without some MAJOR effort... You're better off just buying a 24 valve core and going from there. Open up the 12 valve, inspect it and go from there.
Then - there is NO amount of bore that is going to yield any discernable amount of displacement increase. You have to go with much larger liners and the block has to be precision-bored to receive those larger liners! (You're at a 93mm bore on a 3.0 and you have to get to at least 100mm -
just to get to up to 3.45 litres)! The long-stroke 78mm crank from the 3.2 GTA gets you the rest of the way up to a 3.7 litre!
The crank alone on your current bore gets you to 3.2 and yes - after the bore-increase - you need to rework the heads, so it is more than just the domes fitting the hemis!
Next - the "S" designation is one that belongs to 12 valve engines. It was a mildly longer duration cam that came in the top model 12 valve 164 cars - in the 164 "S" and that has nothing to do with the 24 valvers. The 24 valvers had there own "sport" model and that was the Q with the larger intake runners - supposedly bumping power up to 230 horses over the stock 210 horses of the base "LS/Super" 24 valve base models.
A comparable "S" cam-upgrade in the 24v engines is a retrofit of the 156 GTA 3.2 litre inlet cam into the 164 3.0 engine! (We call it GTA Stage I...) We cut our own GTA Sage II cams that really wakes things up in a 24 valve. Stage III moves the Stage II profile to the exhaust and goes even wilder on the inlet, so now you're changing out all 4 cams!
12 valve cams don't fit the 24 valve heads.
There's much more to talk about - maybe give me a buzz at 425.941.4747 - my advice is free - the work isn't.