I've got a 2003 Topkick. I'm picturing the dash/firewall area, and I'm thinking trying to do a conversion yourself would be a major undertaking. The interior and dash would seemingly be the "easy" part, but the firewall/engine compartment would be a nightmare. The right side firewall houses the heater/ac which is a wedge shaped affair to clear the engine, and even if you could move it to the other side it would be shaped all wrong to clear the engine. And of course the opposite would be true to remount clutch and braking components in the other direction. You'd almost have to cut the entire firewall out and build from scratch. And then I imagine you would need a steering box and components from something right hand drive to work on that side.
I wonder if there were any Kodiak/Topkicks ever actually sold down there for right hand drive? As in maybe find a right hand drive cab in a junkyard to cannibalize or even potentially swap the whole cab? And along the same lines maybe steal an entire front axle and steering gear from any similar sized medium duty truck to swap out for the original?
Just brainstorming, interesting question.