I'm not familiar with Slackware, but if you want something based on Slackware, what's wrong with Slackware itself?
From
The Slackware Linux Project: Installation Help
"For example, if you know you don't want the X Window System, just skip all of the X software set."
Personally, I prefer Debian. So when I want text only install (usually a server of some sort), then I just do a base Debian install. Then, of course, I install whatever software I want to get going.
You could do the same with Slackware, if you want.