LS swap/IRS pinion angle?

[mwj57]

So i'm building a 57 chevy truck with Lincoln Mark viii IRS and planning on running an LS motor up front. I'm wondering what is the preferred angle to set an LS motor at. I understand that with IRS the pinion is fixed and will not rotate up like a traditional rearend so it just hast to be parallel to the motor. I've seen posts suggesting 4 degrees on the motor to prevent oiling issues. Anyone have thoughts on the subject.