1) This is exactly what happens when the engine is starved of oil.
2) This is a relatively common problem on the DR350s because the oil feed line is exposed on the side of the engine.
3) I need a new head
4) ... and so do a lot of other people.
This small chunk of aluminum is proving to be both hard to find and expensive. The trusty ebay has turned up only one hit and the UK-based seller wants more than the bike originally cost, not to mention that it looks as if it's a survivor of the 1666 Great Fire of London. Pass.
Donor bikes seem to show up on CL occasionally, but none are close to me and all seem to have their own closet full of hollow bones.
Next stop are the salvage yards, but based on forum posts, my confidence in finding one in good condition for a reasonable price is low.
I think patience is going to win this race, which is a little discouraging since getting the bike running is the first step. And it needs to be running before I can begin any other phase.