Yes, the 28" VR screw choke barrel is a factory option (send in post '87 SB1 or 2 receiver for fitment) and was on the Topper de luxe. Threaded for Browning Invector chokes.
OOOPS - just reread and noted you wanted a 3.5" chamber. That one does not exist AFAIK. You could have it reamed to 3.5" or if you find a fixed choke barrel with that chamber, I just had Mike Orlen in Amherst Ma, thread me a 20 ga MOD choked gun for Invector tubes. $35 + Shipping.
FYI if looking for a 20ga with screw chokes, be aware that they bore a 12 ga blank to 20ga leaving you with a gun that carries like a 10 and hits like a 20....