Originally Posted by Rincon
...I hope they left some slack inside the wall for me to extend them to be flush with the drywall. Any thoughts?
Who is they? I thought you were starting with bare cement block walls (except for the sealer).
My prefered method is to use 2x2 studs laid flat against the block every 16" on center, and attached with construction adhesive and 2-1/2" tapcons, maybe 4 or 5 per stud. Any protrusions, such as an over filled mortar joint or a crooked block, I chop away with the claw of my hammer. Then I place 1-1/2" foam board insulation between the studs. I generally use 1-1/4" screws for the drywall, but 1-5/8" will do just as well. I never use 1" screws.
Anyway, this leaves 1-1/2" depth (thickness of a 2x2) for electrical boxes. If you need deeper boxes for any reason, you may nave to chop into the block a little to accomodate them.
What inspectorD says about using powder actuated fasteners is a good point - cement block doesn't stand up to the impact very well. But about metal vs wood, I prefer wood for a few reasons. Wood has better insulation value (metal has zero), wood is more rugged, and you can fasten stuff to wood, such as a heavy mirror or shelves. I know metal is quicker and cheaper, but these are at the bottom of my priorities. You may feel differently, just a matter of preference. I like wood.