Per NcStar the "VISM AK KeyMod handguards are designed to fit most AKM stamped receivers with the standard AK barrel profile." It may fit your Saiga, but will most likely require fitting because AK's do not follow a standard pattern which means tolerances and specifications can vary across the many makers of the rifle platform.
Yes and no. The saiga rifles (unless already converted to accept standard handguards) will not be able to use this set. BUT if you buy a standard AKM gas tube AND a lower handguard retainer this should work fine around your barrel. That being said... at the end of the day you'll have spent over $120 with those parts and this handguards set. Plus or minus some shipping costs has etc. At that point I'd suggest getting a Saiga specific handguards set. A few companies offer them and I can at least vouch for the stuff you can find over at carolinas shooters supply. Don't mean to send you elsewhere but i didnt see any saiga specific stuff on this site. Midwest industries I believe makes some that can even cowitness your sights with a red dot.