I am upgrading the insulation in my kitchen remodel. 
the walls are from inside out  sheet rock, 2×4 studs, gyprock, top half 1×4 horizontal strapping with 1 x 6 vertical siding – bottom half brick with 1+ inch air gap and no tar paper or weep holes.  after 70 years the gyprock is still in great condition except light mold where two rows of brick are touching the gyprock [ two rows kicked in to support planter ] it is still sound, just slightly damp. The entire wall has two layers of paint, I know the outer layer is laytex and is very well air sealed.

I have added a second 2×3 stud wall butted up against the outer wall

my question is should i seal the gyprock to the studs along with any seams and dense pack cellulose or flash 1 ” ccspf then dense pack  or  go with 3 to 4 ” ccspf?

Ps   I have converted the attic to a conditioned attic