I suggest that you go direct to your local Volvo dealer. That way you're only paying one set of stock mark-up. Find the nearest one here:
. A word of warning: Volvo Penta parts *are* expensive.
If you have access to boatyards with old Volvo engines lying around, or to automotive breakers' yards (neither of which we have here in Hong Kong) you should be able to save a great deal on ancilliaries (starter motors, alternators and the like) and you may even be able to find annoying little bits like the ball-ended studs of the decompression levers, one of which had gone missing from my engine.
Assuming the engine runs at the moment, and you're just doing a 100,000 hour overhaul, I'd suggest the following:
Dismantle the whole unit having cleaned the outside very carefully with parafin, then a degreaser such as "Gunk" or something similar. As you take the engine apart, take lots and lots of photographs, clean each piece as you take it off, and bag pieces that go together (including the associated seals and nuts and bolts) altogether in clear plastic freezer bags. Label them with an alcohol or xylene-based permanent marker.
Things you'll want to inspect closely with a view to replacing / overhauling include:
Take it to a reputable workshop and have each of the journals measured for taper and ovality. They'll need to take at least four measurements (possibly 6) for each journal - ie: measure the diameter in the X and Y axes at the front, back and middle of each journal. They should record these figures and show them to you to enable you to reach a decision with them on the next steps. If any of the journals is more than 0.0015" (1.5 thousandths of an inch) oval or tapered, have that journal ground down to the next undersize. Record which journals have been ground and to what size and duplicate this information in your log book. Prices in the UK and Hong Kong indicate that you should expect to pay US$ 60-70 per journal for crank regrinding - ie US$320 ish for regrinding the whole crankshaft.
Crankshaft bearing shells and thrust washers:
Replace as a matter of course, remembering to order oversized shells for the undersized journals. New bearing shells from Volvo are ludicrously expensive - mine set me back US$ 470 – try to get these OEM. I can dig out the part numbers and manufacturer for you.
Gaskets and seals:
Replace all oil seals as a matter of course. Try to save as many gaskets as you can. The gaskets which seal two flat metal faces you can remanufacture yourself out of single-ply cardboard (ie not corrugated) smeared with hermetite (a red strawberry-smelling gasket sealant which is non-rubbery and sets hard) if you need to. Exceptions: You must use the proper thickness gasket beneath the mechanical high-pressure fuel pump / metering unit, as this controls the time of injection as well as the volume of fuel injected.