What size engine would you recommend for general haulage from Canada to the U.S.? Is 500 hp too big?
Unless your operation involves a LOT of mountain driving, a 425 to 475 would be more than adequate. 500 is about the limit, in terms of practicality. There are other issues such as the cost of the heavy-duty driveline needed to suppor the engine, but for most applications, a 425 to 450 would be fine.