(1) Track width of the front tires.
(2) Location of the motor relative to the interior of the cab.
(3) Location of controls, such as steering.
These are the things I'd look at before choosing a frame. If you can figure out a solution for those issues anything else can probably be sorted out too.
There is a yahoo group for COE guys and at least one member there has bought an Isuzu and then rejected it because it would not work for him.
