One of the things I noticed about the two Shuul NPCs detailed in the campaign setting - the Agent and the Technician - is that they would have some difficulty to compete once your pesky PCs got up close and personal.
I therefore adapted the 'Defender' stat block from the Ptolus campaign book, maintained their techno stylings by keeping the Leather Coat & Protective Goggles but added the Shielded Double Pistol and Battleaxe. I utilised the battleaxe as it is both dwarven (nodding to the ancestry of the technology in use) and there is also something a little more punk about a hatchet rather than a sword.
I think these would be great for set piece encounters in either The Tower of Science or The Foundry. If you are using the Shuul more as protagonists, and leaning in to the Zaug influence, perhaps Shuul agents have discovered a cache of Chaositech and some Shuul Defenders are there guarding it before it can be assayed and extracted.
Important to remember that it's likely the Shuul Defender will only get off one salvo of gunfire before falling back on their battleaxe.
Some nice additions if you want to up their combat effectiveness could be:
Give each a Shuul Pill, e.g. of Healing, Darkvision or maybe even Haste! This will allow them to make use of Bonus Actions!
Give one or more a Tanglefoot bag - and stop those PCs from getting around your front line!
I utilise a slightly different approach to guns than described in Ptolus, in that:
"After making a number of attacks specified by the weapons reload or long-load number, you must reload the weapon.
RELOAD: weapon must be reloaded using an action or bonus action
LONGLOAD: weapon must be reloaded using an action
If you wield two 'Light' firearm with the 'reload' property you can reload both with 1 action.
It’s up to you to decide whether a character has proficiency with a firearm."
I will do another post referring to the firearms mechanics I use (and where you can find them).