Why wouldn't one be able to upgrade from 32bit 12.2 when you can build a multi lib slackware OS?
I saw that upgrade from earlier version than 13.0 is not supported technically but it is doable and am finding enough posts of people who have done it and solved issues in the forum, it is a great learning opportunity, I get to discover the what, where, when, why, and how, i love it!
I started out with a Howto from Rob Workman on some slackware blog, its bookmarked on my other computer. Come to find 1 issue has to do with partition types ie. ext 3 vs ext4 I have to take a closer look at the straight install documentation. In any case i have the directory on my PC a good start and my 12.2 install is working fine still because I did not change the kernel existing install. I will build off what i have and transfer to its' own partition for a slackware64 current mirror. When I have it working I will install onto the 64 bit PC.
In any case slackpkg 2.8x worked great and did what it was supposed to do... issue was the version I started out with it was too old but good enough to download the one I replaced it with