http://xssights.com/index.php?nID=sight ... D=tactical
For a relatively small spend, that would let you put a large rear aperture and front post onto the SP-1, complete with tritium lamps.
There are also lots of optics that come with "carry handle mounts" like this:
Or you can get a "drop-in" solution that will let you mount any standard scope to your carry handle:
http://www.nightvision4less.com/leu-521 ... 6-mat.aspx
In terms of what optic to put on...a low magnification, large objective scope can work well on nights with good lighting from the moon...but nothing quite measures up to good night vision technology when it comes to operating at night. The problem is that it's not cheap. At all. Especially if you want good equipment.