differences in the blocks between 3.0 and 3.2
 

What are the differences in the engine case between 3.0 motor and a 3.2 motor? Are the cases the same ?

The cases are the same except the Carrera hasn't got an oil sump but it does have a boss on top for a Z1 sensor that today is worthless and it has 2 bolt hole bosses for the flywheel sensors that may well be able to be duplicated.
Bruce

OK, so I could technically use a 3.0 (SC) block and build it out to a 3.4?

You need the crank and rods from a Carrera and the cylinders from a Carrera opened to 98 for the sealing taper to the heads.
Bruce

When you say Carrera, do you mean the 3.2 motor?

Yes. The crank, rods and 23 mm wrist pin is the 3.2
Bruce