Zep Frame/Headset Question

[Talewinds]

Hi all, does anyone have experience with the Zep frames and the headsets used on'em? I dismantled mine last night to discover the headset cups, which I knew ahead of time were replacements, just fell right out of the head tube. Tried some other "standard" headsets and the cups are all too small. I can tell at first glance the head tube has a larger diameter than other frames in my shop.
Fill me in??

* Also, looking for a Zep tank!