Vman, It sounds like your lifters are not working correctly. Can you get the engine to idle down by backing each one off, even to the point of being loose? If it does, then is just a lifter problem and another set should cure it. You should be able to go at least a full turn and half down with out any problem. You do have to go slow and wait while the engine catches up to each adjustment. It takes awhile to do so give it time.
With a 70,000 Mile set of worn bearings, I sure wouldn't worry about the oil pump, plus you already told me its a low rpm cruiser, not a high rpm racer. And about the oil, you don't need the heavy diesel oil if the cam and lifters already have 70K miles on them. Just pick up any brand of oil you like and add one can of Mellings or Crane oil additive if you want extra protection. The heavy oil is just extra work for the pump, gears, and distributor. I run Mobil 1 5W20 in my engine with out any problem and no additive. Once the cam is broke in, any of the new oils will work with our type of engine. Its the killer valve spring pressure and radical cam profiles that need the extra protection, not a stock 6 cylinder cam! Joe
