Mounting TV on Thick Drywall + 1" Stud + Concrete blocks
I don't think it's safe to assume the firing strips (what you are calling studs) were installed in such a way to properly hang a TV. Unless you know for certain otherwise, you shouldn't mount the TV to the firing strips.

I think you have three options.


Find a fastener that can go all the way through your bracket, stud and drywall, and anchor in to the concrete block. Is your concrete block hollow? If so, you can get pre-packaged toggle bolts that are that long.

PROS: Minimal damage to drywall.

CONS: You need to be able to drill a fairly large hole in the block very deep. If you don't have a powerful enough hammer drill or appropriate bits, this can get pricey.
Remove the drywall down to the concrete and firing strips, and install plywood. Use easy to install fasteners like concrete screws (Tapcons) to mount the plywood to the concrete, through the firing strips. And then put drywall over the plywood to get the wall back to the correct thickness. Mount the TV bracket to the plywood using lag bolts.

PROS: Easy to do, comparatively. A regular drill can handle this, but a hammer drill would be better.

CONS: Messy and time consuming. Large drywall repair job when you take the TV down.
Use a spade bit or Forstner to drill a large hole in the drywall down to the firing strips. Then use concrete screws (Tapcons) to securely fasten the firing strips to the concrete block. Your TV bracket can then be screwed using lag bolts directly to the firing strips.

PROS: Minimal damage to drywall. You might be able to do this without a hammer drill.

CONS: You have to use exactly the right lag screw. Too long and the screw will hit the concrete before it's holding the bracket tightly; too short and you risk pull-out.