1x4's would be a little odd, but I wouldn't think it was way out of the question. The problem you are going to run into is that those aren't going to be strong enough to hold the weight of the TV. You are going to need to get anchor into the block, which if you should be able to do fairly easily! Note that sometimes the place you bought it might be able to do this for you. On the flip side, when I live in San Francisco, I had a
San Francisco handyman that would help me with these types of projects. Now that I live in Florida, I don't have anyone yet. If you know someone who has done this, you might ask who they used or ask them to help you! A TV is a terrible thing to break!