Moving forward with a failed Engine

I remember removing and inspecting the fuel tank prior to towing the bike for repairs, when I found a thick mixture of corrosion and what seemed to be mud accumulated in the tank. There also was an occasional drop of water that trickled from the underneath of the engine, which we didn't take too much notice of.
However with the completion of the electronics when we removed the carburetors we found them waterlogged and full of gunk. Recollecting that the bike was left in the open to face the elements and a couple of monsoons, we suspected there was a chance water might have found it's way into the engine.
We had no choice but to take down the engine and do a proper inspection. Which Mr Rohan agreed to do the next day.

Sure enough I get a call the next day from Mr Rohan's son Chathura who asks me to come by their place, that there is something I need to see.

Wasn't a prettey sight, the total oposite.

Not something I wanted to see; not what I expected when making the purchase and most certainly not what I was expecting to spend on. A total rebuild of the engine

Opening the engine we find that it has seized due to taking in water and the subsequent build up of corrosion over an extended period of time.

Our worst fears have come true. Just overcoming one obstacle I face a new one.

 A close look at the sump reveals the absence of engine oil and that one side of the engine has sustained more damage.

The piston bores are completely covered in corrosion. You can imagine the condition of the piston rings. We had unknowingly kicked on the kick lever making the internal components move and might have caused further damage.

 The Crank reveals corrosion and needs to be repaired with new bearings, pushrod etc. The worst part is if it cant be repaired it will have to be replaced; only there are no cranks in the local market and importing one will cost me more than the bike itself.

Thankfully the Gearbox wasn't affected and the pistons were salvageable.

Rebuilding the engine was not something expected and incurring such cost was going to be hard.
At this point it gets quite depressing.
However you cant turn back now. Got to keep moving forward even with a failed engine. As they say... What to do?