Have you contacted Lamborghini? They ‘tweak’ old truck engines and might have an old one lying around :witless:

You’ll want to upgrade the steering anyway, if for no other reason than the extra weight of the V10 over the original flathead 6. Your best option is probably to swap in a Mustang II style front suspension. That way you get rack and pinion steering, and more aftermarket suspension and brake options than you know what to do with. The I beam axle isn’t up to the task of controlling the truck with that much power either. Last time I did something like this it was an Aston-Martin Vanquish V12 in a ’39 Zephyr. We ended up making a whole new frame for it to accommodate all the necessary changes.