An engine that ran 1/4 mile with a split oil pan is likely that it didn't turn off soon enough to save the turbo. If it slowly leaked out and if the sensor is actually working, then MAYBE it's ok.
I have to disagree that the #4 cap is the one that will show the damage. The interesting thing about the ALH oil pump is that it is so good that it will drive oil OUT of an engine. The oil pump will pump air. The first place the air will go is to the #1 cam cap, #1 rod and Main bearing. This has been evidenced repeatedly.
The journal which can least stand the strain is the #1 cam cap, as there is only aluminum against the cam itself... no journal bearing. So, that is the FIRST place to look and quite honestly, the easiest.
If the rest of the engine looks good, and there are no bearings that have more heating than a straw-coloration on the journals, reassemble with new bearings and bolts.
If you think the turbo is ok, the best thing is to check it after a few miles after the engine is heat-soaked. If the turbo compressor wheel has turned black with oil or you see that the intercooler is filling with oil, you have lost the cartridge bushing for the turbo. Replace the turbo. It is better to be pre-emptive on this point, as a runaway turbo will very likely end the engine's life dramatically.
X2 if it's an automatic, as there is no way to stop a turbo runaway with the autos.