Aftermarket bullpup chassis configurations are prohibited, factory bull pups are fine, T97, Tavor, RDB etc.
But bullpup chassis for a conventional layout firearm like an SKS or this is a big no-go. It’s treated like illegal modifications.
PROHIBITED DEVICES
Former Prohibited Weapons Order, No. 9
1. Any electrical or mechanical device that is designed or adapted to operate the trigger mechanism of a semi-automatic firearm for the purpose of causing the firearm to discharge cartridges in rapid succession.
2. Any rifle, shotgun or carbine stock of the typeknown as the “bull-pup” design, being a stock that, when combined with a firearm, reduces the overall length of the firearm such that a substantial part of the reloading action or the magazine-well is located behind the trigger of the firearm when it is held in the normal firing position.