Tony,
Don't have much experience or familiarity with BSA but a search on the web or collectors/gun values handbooks might turn up some history on this brand which used to be imported. Believe it was a British company who may or may not have made their own firearms. If memory serves me correctly, I think Ithaca rebadged BSA rifles for a time. Not sure what you mean by is the stock functional but as long as the stock feels comfortable to you and is aesthetically acceptable, I'd consider it quite functional. Since it is a caliber you want and not readily available and if you are comfortable with its price/conditions and it fits you, go for it.