My 2 cents worth.
I have seen many young talented 400m guys who ran just under 50.0 for 400m struggling to break 2:00.0 in the 800m and have also seen many longer distance guys who run around 54.0 for the 400m comfortably break 2.00.0
Based on these differentials and assuming Wariner falls into the first category I assume he would run around 1:47.0 which would be world competitive but not world class.