[Walt Fricke]

You might explain a bit more what you are up to.

Good compression (and good leakdowns) usually indicates that the top end is OK. In which case, why would one take it apart? Rendering moot the issue of splitting the case.

Splitting the case is for main bearings (rods, too, if you want to use bolt stretch), checking crank, checking for line bore, dealing with IS gears, oil pumps, and sundry other things. Of course, if you wonder about those things, you'd do a full teardown, as it is not easy to figure out externally if all this stuff is still just fine. With race motors, guys set a number of hours between teardowns. Shops with lots of racer customers often have good data on this. The rest of us mostly guess, or watch out oil temps carefully as hours accumulate. But with an engine of somewhat unknown history, there is a certain amount of pig in a poke at work.