BB LWP PS Setup Help - Pics/Advice Please.

[mole2000]

After searching a while I just haven't been able to find any good pics of a BB with PS. I was asked today whether I needed a single or dual pulley and I really have no idea. How can I determine this? My crankshaft has 3 grooves with alt belt on the outside groove and also on the single groove water pump pulley, leaving the inside 2 grooves empty. Would that indicate I can use either a single or dual pulley on the PS pump? I used the March Perf bracket for PS. Unfortunately no pics of that yet...

Thanks!