It was good to go as imported, but you added an evil feature that it could not have had and still been imported.
When you say kit, what do you mean?
Just the add-on stock/pistol grip that retains the factory FCG, or a full conversion kit that relocates the trigger and includes a FCG?
The answer depends upon exactly what kit was used, and what parts were replaced with USA made items (including mags).
It cannot have more than 10 imported parts from ATF's list:
(1) Frames, receivers, receiver castings, forgings, or castings.
(2) Barrels.
(3) Barrel extensions.
(4) Mounting blocks (trunnions).
(5) Muzzle attachments.
(6) Bolts.
(7) Bolt carriers.
(8) Operating rods.
(9) Gas pistons.
(10) Trigger housings.
(11) Triggers.
(12) Hammers.
(13) Sears.
(14) Disconnectors.
(15) Buttstocks.
(16) Pistol grips.
(17) Forearms, handguards.
(18) Magazine bodies.
(19) Followers.
(20) Floor plates.
So if it's just the add-on grip/stock that retains the factory FCG and you haven't replaced anything else, it is non-compliant.
Tapco has a pretty decent summary:
http://www.tapco.com/section922r/ETA:
As well as gunwiki:
http://gunwiki.net/Gunwiki/BuildSaigaShotgunVerifyCompliance(Sporting purposes? I don't remember reading anything about sporting purposes in 2A.)