for an Asian procurement, I'm looking at a stripped Toyota Coaster bus as the starting point to convert into a relocate-able office. I use the term "relocate-able" rather than "mobile" because there will never be a need to go faster than 25 mph. The thing won't be more than once a week or so.
That being the case, the OEM 4.0 Liter diesel engine seems like significant overkill and wasteful.
Is there any feasible way to strip out the motor from a factory-delivered chassis, replace it with a smaller motor, than sell the 4.0 to a coachbuilder or bus-repair guy?