Short answer: As long as you're compliant with the TV/mounting documentation and there aren't significant defects in the studs (e.g. termite damage, water damage, etc) you should be fine.
Longer answer: I did this fairly recently and my advice is as follows...
Make sure you purchase a TV stand that is rated for the size/weight of your TV. The specs on the site look pretty beefy but don't take any chances. Consult your TV manual for mounting details. Most (if not all) TV manuals will explicitly specify the weight of the TV and what VESA mounting pattern is required.
Confirm what's included in the mounting kit and what surfaces it's rated for. The mount should explicitly say what its rated for and what's required. Our mounting kit (different brand) came with two sets of screws (1 set for concrete and 1 set for wood).
Get a mounting kit that supports heavier weights and multiple VESA patterns. If/when you ever upgrade the TV, you don't want to have to replace it. :-)
Have a friend help. Installation is waaaaaaaaaaaayyyyy easier (and much safer) when multiple people are involved.
Check to see if the mounting kit lets you make small adjustments AFTER it's mounted. After setting (and re-setting) our TV mount several times, I later learned that it had the ability to make slight tilt modifications while mounted. D'oh! This saves gobs of time and is an awesome feature.
Lastly, check out these posts here for other insightful info:
What's the least intrusive way to find out what's in a wall?
How do I run wires for a wall-mount flatscreen TV?
Do not use drywall anchors to hang a TV that large on a swivel mount. If it was a mount that didn't have motion, I might say that's acceptable, but not with a swivel mount.
You will need to use wood in some form to add the necessary strength.
Plywood can be attached to the wall studs using 3-1/2" lag bolts with fender washers. To provide a clean finish, the drywall can be cutout and the opening filled with the plywood. Then tape and mud the joints. Sand the surface smooth, prime, and paint. The plywood will be barely noticeable if done right. Be sure to match the plywood thickness to the drywall thickness.
If you do not want to remove any drywall, the plywood can be mounted directly over the drywall. You will need to use at least a 4" lag bolt in this case to account for the extra depth of the drywall. The plywood can be finished with a routed edge, sanded, primed, and painted for a finished look, if desired.
A final option for a truly hidden mount would be to open the wall by removing the drywall. Then install 2"x4" crossbracing between the studs at the correct locations for your TV mount. Replace the drywall, tape and mud the joints, sand, prime, and paint. The bracing is now hidden in the wall and you can attach the mount to the bracing.
Best Answer
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.