I've had this ordeal before and its frustrating cause things don't move along all that quickly. Anyways, since i have a plasma premium frameset i'm selling, I took the liberty to check out the headset bearing and measure its diameter to 1.5in. I assume the inner diameter would be whatever fits the plasma premiums steerer tube?

I can bust out the tech equip to measure it precisely if you need but im over getting all that out.