Certain fabrics are advertised as not needing rib stitching if the ribcaps are of a size that allows gluing only. However I wouldn't feel safe without it. There are several variables and this type of information is becoming a lost art due to all the "old boys" retiring.
Pm me if you want with the following info and I may be able to help, but would say the best bet is if you can find a more local inspector who has knowledge of fabrics to inspect the a/c for you.A list is available on the LAA website.
What type of plane,where do you think its missing i.e wing / tail ,how far from the root etc.
What type of covering ?