Alpina used the same designation B12 for both the 7 and 8 series models they sold.
So a B12 could be a 740, 750 or 850 converted to their Specs.
Alpina is actually considered a Manufacturer.
An Alpina is titled as an Alpina, not a BMW. That is why you don't see real Alpinas here in the US.
Because the VIN is not BMW, importation does not follow the simpler rules that bringing in a Euro BMW does.