In addition to what veritech said, surely you dont wanna use that big ol' Holset on that little RB, so in your interest, I'll go ahead and hold on to your Holset for you..... I'll keep it warm for you until you need it again....
Seriously though, Id grab the RB.. theyre cool motors and not seen all the time...put some oil in the cylinders and cover it up in your garage.. you'll figure out a use for it.
At a minimum, its a kick-a conversational piece while you and buddies are drinking beer in the garage...