Using iTunes Match to merge various iTunes libraries?

I have a bunch of old external hard drives with about three or four old iTunes libraries. If I recall correctly, none of them have overlapping songs, but since I tend to "start fresh" every few years and simply get a new hard drive, do a fresh installation of Mac OS X, and pull up necessary documents from the old hard drives, I've inadvertently dug myself into a mess where I have multiple iTunes libraries.

Instead of reimporting into my current library, which I can't do since I don't have much free hard drive space, could I take turns starting up my Mac from each hard drive and enabling iTunes Match? At the end, wouldn't Apple's cloud be agnostic as to how many hard drives I'm doing this from? I'd love to have all my music accessible from the cloud without needing to attempt to actually merge the contents of any of my hard drives and iTunes libraries. Thanks!