Colin you're right. Fry has stated that with the exception of elaphe, pseudelaphe, pantherophis, pituophis, lampropeltis and their like, all colubrids produce venom.
However, not all of the remaining venom producing colubrid genera are opistoglyphic.
.......and to further what's all ready been stated - pantherophis are neither venomous or rear-fanged.
Reading scientific papers is fun..........reading the forums, however, can be infinitely more entertaining.