Differences in VIN "3" and "C" engines

As I've been doing my engine rebuild I have started running into this important engine spec. I had to buy special METRIC piston rings for my VIN "C" LN3 engine. I know that VIN "C" engines have a balance shaft and Hydraulic Roller Lifters. And I have recently run into some info [see link below] that indicates size differences in the valve sizes. Upon measuring my valve stem diameter, 0.3408", according to this article, points to my Cylinder Heads being for a VIN "3" engine. I'm not sure if these engines had interchangeable Heads. If my Cylinder Heads are for a VIN "3" engine, but my engine is in all other respects a VIN "C", should i consider buying VIN "C" Heads? Can anyone verify the info in this article? And lastly, are there any other differences between these engines I should know for buying parts for the upper half of the engine?

http://www.ehow.com/list_7355755_difference-delta-88-royal-brougham_.html

I think if there are enough responses, this can be a very informative thread for others on here who have late '80s and early '90s Rivieras.

If they take the same head gaskets, based on what I read there, the heads should be interchangeable. Sounds like it's worth trying! Larger valves = WIN!