47-59 57 Chevy pickup power brakes

[garrison]

My truck is stock except I used lowering springs to drop it a few inches. Still 235 and three speed column shift transmission. I'd like to add power brakes. I found an older thread about it but some links were outdated and it pertained to a 4 speed.

My question is can I install a power brake conversion kit without having to change the crossmember. I'm not super mechanical and that thing seems to be riveted on with huge rivets. I also wonder how much difference it make as opposed to simply switching to a dual chamber master cylinder?

And finally, those that have done this, what kit/vendor do you recommend? Classic Parts of America (formerly Chevy Duty) is local and I tend to go there, but their site does say a new cross member may be required.