Will this work on my part?
Before anything else, the optics have to allow it. If the smallest defect you care about lands on fewer than about three pixels, no amount of modelling will find it reliably. This works that out from your part size, your defect size and a camera resolution.
Usually the long side of the part, plus a margin for how accurately it is positioned.
The size of the actual flaw, not the tolerance on the drawing.
Pixels along the same axis as the field of view above.