At this point, everything is pretty much ready to go back together, or so I thought. As I was rearranging the timing chain to allow me to slide the gasket and head on, I discovered that the timing chain tensioner guide was chipped and missing a clip. That means that the front cover has to come off, so at this point I decide to just re-seal everything. Remove the crank bolt with a big breaker bar, pull the front cover, pull the oil pump pickup and pan, etc.
Head anxiously awaiting installation:
Oil pan, with the pickup in it, full of sludge and other assorted detritus. The pickup was all sludged up too, so in the end it was good that I removed it.
Oil pumps on these are fairly notorious for unscrewing themselves over time, especially with high rpm use. Not wanting to risk it, I loctited and safety wired mine.
New guides and oil pan gasket:
While I was in there, I also replaced all of the coolant hoses and some of the fuel lines. Regardless of what happens (keeping the M50, swapping in an S52, etc) I'll probably be glad it has new hoses. One less thing to think about, even if they bump the budget up some.
Head reinstalled, waiting for the valve cover:
No pictures after that, but it does run and drive now. There was so much coolant in the exhaust from the cracked head that it didn't want to run smoothly, and it smoked like crazy. The last 50 miles of driving has cleaned it out pretty well, and it is running much better.
Downside is that it keeps building crankcase pressure as a result of filling the CCV breather with water/emulsified gunk. I don't know if the HG is still leaking or what, but when I get back from vacation, I'll pull the drain plug. It has been sitting for 2 weeks. If any real amount of coolant comes out before the oil, then I definitely still have a leak somewhere. Signs are pointing this way anyway - the cooling system doesn't build as much pressure as I expect it to, and the coolant level has dropped somewhat. It's hard to say for sure if the latter is caused by air in the system slowly purging, but it seems slightly excessive to me. I have a cooling system pressure test kit coming in the mail, which may be able to shed more light on that situation.
It's a little discouraging to have not fixed the issue, but I guess that's the nature of projects. Hopefully I'll know more next week, and figure out where to go from there. On the plus side, the car drives very well, there are no thunks, no rattles, and it goes down the road straight. There are a few surprise electrical issues (maybe not so much of a surprise, actually). The aux input on the Alpine head unit doesn't seem to work, the driver's side door tweeter doesn't work, power locks are intermittent (alarm chirps but nothing happens. Opening the door sets the alarm off), the rear hatch window likes to open itself while driving down the road, and the main hatch latch switch only works about 5% of the time. As a result, as soon as the engine thing is figured out, this is going to become a '90s electromechanical troubleshooting thread!