I'm closing in a hole about 5' x 5'. Based upon the width of the wall and
true width of a 2' x 4' that will be used to frame the hole, I'm left with
3/4" on each side. If I use 5/8" drywall, I will be 1/8" shy of a level
surface. Should I use this method and then fill in the 1/8" with compound
to bring it up or should I rip 1/2" off the framing material so I can get
1" on each side and double up 1/2" drywall on each side to get the drywall
flush with the existing wall? If the latter is the best method, should the
pieces be glued in some way before they are placed up or should the normal
act of screwing them to the joists be enough?

Thanks,
C