What you really want is a Cat3208NA. I'll even sell you the bus.
(I believe the rating goes dt466, cummins 8.3; then dt444, dt360, cummins 5.9.. Cats at the back, but a 3208TA has gotten good reviews. Get turo'd for sure, preferably aftercooled.)
Good choices, not in order:
DT466.
DT360.
Cummins 5.9 or 8.3, except the 98-02.
Ford 6.6/7.8
A cat 3208T is surely a few steps ahead of a Detroit 8.2
Avoid the 8.2 if at all possible, unless you get the bus for less than $500.