If nobody has already said, as far as the missing parts you could join ACMOC and see if any of those people have them or know where you can find them. Somebody on there may even be able to fix you up with a used piston and liner if needed
I bought an old Ford backhoe a few years ago that had the can over the exhaust. One of the first things I did was get a tink-tink flapper, because I knew that I would eventually forget the can.There is no D318 rebuild kit (that I've been able to find anyway). You need to piece it together. Piston/cylinder kits are 250 bucks per hole (1500 for six). A set of main & rod bearings are about 500 bucks. A gaset set is about 600 bucks. And for the head - new valves? New guides? New seats? Or a simple valve job? Who knows? To rebuild a D318 one can expect to pay about 3 grand in parts (D318 parts are not cheap). Plus I'm looking at an extra 1200 to purchase six new injectors. Not sure what it costs to turn a D318 crank, but I'm assuming it costs more than turning an automotive crank.
I suppose I could try to dislodge the sized pistons and hone the cylinders - maybe replace the rings - slap it back together with a 600 dollar gasket set. But I'd still need 1200 dollars worth of injectors. Said another way, the most hillbilly get-it-running method will still set me back 2 grand. To rebuild it right, maybe 6 grand?
It is much more cost-effective to find a running D318 engine and drop it in. Or repower with a different engine.
Here's the what's puzzling me - the previous owner left the coffee can off the exhaust, and the engine filled with rainwater and seized - which doesn't say much for the previous owner. Dude could've installed a 30 dollar flapper on the exhaust pipe, but that would've cost him 30 dollars - so he went with the coffee can from under his sink. But I digress. After the engine seized, the grader was donated to a college in eastern Washington. The school's diesel department started the process of pulling the engine, and then they gave up and sold the grader at auction. So why did they give up?