I found this FAA interpretation letter from March of this year that clarifies most of the gray areas of 121.436. I'm assuming this is what NovemberBravo and his all star class found in their Google search, however I won't be an arrogant douche and I'll post it here for ya:
http://www.faa.gov/about/office_org/...rpretation.pdf
Long story short--cargo-only time doesn't count if the seats are removed, regardless of the original type certificated seating configuration of the aircraft.
On a side note, this isn't even something that affects me personally, but I strongly believe that all pilots should always help each other out on stuff like this and discuss the regs. Maybe I'm old fashioned, or maybe I've just done too many meetings as a union rep where conflicting interpretations happen all the time, but NovemberBravo I think it's really, really bad karma to be a douche about your internet searching skills instead of sharing whatever info you have about something.