While I haven't modded the Retaliation Roadblock as a default Roadblock yet, I think something similar to what I did with my custom Roadblock would work for the Retaliation torso as well:
I just swapped out the knees with Resolute Snake Eyes. The only problem is that you will need to either sand or dremel the upper legs to allow the knees to have full range of movement and for him to be able to stand up straight. Again, a dremel would be ideal, and doesn't take long at all to do.
I just don't care for the Retaliation legs at all, as they make him too tall, and he looks disproportionate. I also can't stand how high the head-sculpt they gave him rests on his neck. That can be remedied though as well. I've actually been wanting to do another custom Roadblock similar to the one I shared above, but I want to use the Retaliation torso and arms instead, and a different head-sculpt.