there are no specs AFAIK, or could find. though Memory Alpha says
Viewed from the exterior, Gomtuu was a
massive, dark-colored starship shaped like a sunflower seed shell.
"massive" for me suggests a vessel larger then either the Galaxy-class (size class 8) or the Romulan D'Deridex-class War Bird (size class 10) though I would say smaller then a Borg Cube (size class 16) so maybe size class 12-14?
some pics for you
AKA-Dean
"I will never make excuses for who I am. It is the way I was born. I am a HUNTER. a BONE COLLECTOR."
Wave Man, the term "wave man" is the English translation of 'Ronin' (Japanese word) and literately translates to "wandering person" and in a modern context a WaveMan is one who is socially adrift or a SalaryMan who is between employers.