Hi. If you got the normal (not the XL) Acorn Tank, you'd be looking for the smaller (~.8-1ml,) steel tube CE2. The XL (~1.8ml) CE2s will be too long, and the clearomizers are slightly larger diameter and a bit weaker structurally.
I'm not sure if you can use a clearomizer with the tube pulled off, but it looks like that may work. The pre-cut ones on their site may be your best bet.
I'm not sure if the original CE2s for that tank were Bauway or RoyalSmokers, but I just don't see many steel-tubed ones around anymore. Most places seem to be migrating to clearomizers by Vision.
Speaking of Vision, you may want to look into the Vision Vivi Nova. It's rather new, and has had some problems, but it looks as it the v2.5 is working pretty well. It's fairly cheap, nice-looking, easy to (dis)assemble, and has replaceable innards. I'd recommend reading a bit of the beginning and end of the thread on it in the GotVapes forum before buying.