Mini 4x4 Kubota Tractor with Major Issues.. Can We Bring It Back to Life?

I bought this Kubota 4wd diesel tractor a few months ago as a non runner, last time the owner tried to start it, the engine locked up. Turns out he had left it out in the rain without a cover over the exhaust, water entered the engine and it hydro-locked when he turned it over. Lets fix it.