Doors and Windows - extended strike plate

I have replaced my back exterior door with a newer one. Because I have an old house, the walls were very thick so the depth of the door is larger than normal. My brother stated I needed to get a bigger strikeplate, so that my door fits tight. My question is.....where can I order a longer strike plate? Will home improvement stores like Lowes be able to do that for me? If not where should I turn go to order one.
Also how is it measured? from the edge to the curve of the strike plate?

Any info will be greatly appreciated.
Thanks!

If I understand your problem correctly, you installed a door (probably pre-hung) with a 4-9/16" jamb (that would be for a 2X4 wall) in a thicker wall, and set the jamb flush the exterior of the wall. Now the latch hits the inside wall when you open or close the door. You are looking for a strike plate that extends far enough past the door jamb to prevent that.

I've never seen one. Best solution I can offer is to re-install the door so that it is flush with the INTERIOR wall and add a jamb extension to the outside to bring that out flush with the EXTERIOR wall. Now you can install the exterior trim and the interior casing, and the standard strike plate will work just fine.