Just to clarify: your property will be global, that's for sure. But your requirement is "Our users would like to have a "Solution Build/Version Number" displayable on the Presentation Template on all Item Types." (my emphasis).
You cannot expose a property, so I guess you will have a field used by all types that you populate via trigger with the value of the property. And then, when the value of the property changes you update every item in the database?
This is how I would do it, without property:
1) Create a type used as singleton, with a field for the Solution Number. Create singleton and set field value.
2) Create an IBPL used by all other types, automatically populated to point to the singleton (not editable, of course, maybe not even relevant).
3) Create an FVA to the Solution Number, used by all other types.
When you update the singleton, all items reflect it without any work or data modification.
In this case, the singleton could be the MKS Solution type, but since you're not using a property any more,why use it? To me, the added benefit is that when the time comes to have different build numbers for different cases (I'd be shocked if that day didn't come), you're all set. All you need is to point different items to different builds.
