As long as you don't increase the height or length of the panels (which you can't, lol) then they should hold up just fine because they were already used with that same height and length. You will have to add bracing though, but that shouldn't be a problem.
is it the standard like 1.5' tall? or whatever most 55's are? I'd say you'd need a good good euro brace or at the very least reinforce the corners. That would scare me at 4x4 with the thickness most of those 55's come at .
Thank you everybody. I'm gunna give the braces a try. I will leave it the basement filled for a while and see if it gives way. Start the build this weekend!!