David,
I think you are wise to question the longevity of the tandem pump if the suspension has been changed over. These pumps do rely on the fluid for internal lubrication. It was a bit easier on the 6 cylinder cars as the pump could be removed from the front of the engine, and a blanking plate installed. Not so with the V12. I think the best option for you would be to replace the pump with the non-tandem pump used on non-levelride V12's. It has a modified housing to keep the drive pulley in the same place, but no second pump. Then you can remove the pipes and such, and the worry would be over.
Cheers,