One important bit of information which was not provides is gear ratio.
Besides the nameplate rating, it is always important to consider elevation changes (hills?), speed (hp) needed, and presence (condition) of trailer brakes. I routinely drag around 15k 5th wheels and up to 6k tandem bumper pulls with my wore out SWB K10 (305,700R4) with 3.42 K20 running gear. But only local, no hills and at low speed. 5th wheels always tow nice, bumper pulls not so nice..