What to put on top of a Karlson?

[Illusus]

A few months ago I built a pair of Karlsons; JBL E-140 drivers, for some jam/recording sessions... since then they've made their way into my listening room. I'm running them with fostex 166es-r sitting on top in open baffles, biamped, xo'd at ~300Hz. Sounds pretty good, best bass dynamics I've heard at home, so far...
...but, I want to use the fostex drivers in another project (one of those fancy, spawn double horns) and keep the karlsons for rockin' out. The OB fostex is not that good of a match, even after playing around with eq it doesn't sound "right". What is a good match for the karlsons?

I'd like to spend as little as possible (who wouldn't?) and get a good match in dynamics without much hassle (eq-ing... etc). Some type of front horn is my best guess but I don't have much experience with front horn design.