Just remember that Moroso, Barnes and most every Dry Sump manufacturer DO NOT recomend Fine filters BEFORE the scavenge sections, but Do recomend them on the Pressure side Out of the pump to engine.
Most mechanical pumps (oil, fuel, etc.) do not appreciate restrictions of flow coming in.
Moroso recomends (and I run) Moroso inline filters on the scavenge side which are fine enough to keep any particles big enough to hurt the pump.
The clearances in the pump are not like engine bearings, and even if they are slightly scored will not likely be of any concern.
If you plug up the filters on the scavenge side with debris, not only will you lose the engine, but you will most likely get to buy a new dry sump pump too.
On the other hand if you are buying a used pump, keep in mind that if the rotors are "gouged", the aluminum case is probably no good and will need replaced.
This is usually caused by not running "inline coarse type (Moroso)" filters on the scavenge side when catastrophic engine failure occurs.
One more note of caution on buying a used pump: if it does not turn freely by hand when empty (and minus fitting caps), the shaft is most likely bent from being in a crash or dropped on the pulley end.