'83 Euro Intake Port Size
 

There is some conflicting information out there, can anyone point me to a definitive source regarding the intake port size (large or small) for an '83 Euro motor ?

All the euro or ROW are large port. Small port was for the US Lambda system cars.
Bruce

Intake ports are 39 mm for a large port SC

So if you have one damaged '79 head any ROW SC head would do as a replacement?

Yes that is correct. The early big port SC heads will have the air injector hole in the exhaust port that will need to be plugged. If you are using the air injection on an early SC, the late ROW big port heads would need to be drilled and tapped for the air injector.

Hmm, my '82 SC 930/16 has air injection heads.