[v8volvo]

Yep, Larry's is a good shop. They are the only other shop in town besides ours that has the correct tools and know-how to work on diesel Volvos. I will be interested to know if the O-ring you get is the right kind -- let me know. Those guys have been the only show in town as far as Volvo diesels for a long time so they may know some things that the rest of us don't in terms of getting parts, etc.

If the valves were done when the head was at the machine shop (which they should have been), then they are probably OK but it doesn't hurt to check them. If your valve cover gasket is the 1-piece rubber type it can be reused forever. If you have the old 4-piece cork kind it's worth upgrading to the rubber type anyway since it doesn't leak.

Glow plugs don't erode, so if yours all match then that's not your issue. The compression readings are on the low side, though. My '86 wagon with 271k was right in the same ballpark as yours, maybe a tad higher (I think there was only one cylinder that was in the 300s). My '83 764 had all 6 above 500psi when I checked it a couple weeks ago. The compression could account for part of the running issues you're seeing. If you don't already have synthetic oil in it, you might try running some fairly thin-grade syn (5W30) for a while and see if it helps free things up. If it has been run on dino oil its whole life the rings are probably pretty gummed. Lubro Moly makes a 5W40 semi-syn "Anti-Friction" oil that might also be worth a try. It has some kind of molybdenum or other kind of special substance in it that gives it a sort of silvery appearance right out of the bottle, kind of like it has anti-seize mixed in with it. Looks scary but it had a positive effect on an '84 244 Diesel with weak compression that now runs strong, so might help yours out too.

Sounds like the car has really been looked after. It's always nice to get a fat stack of receipts that show someone has cared about it. Who has been doing the work on it up to now?