Leave it open. When you start to see it's imprint on the case head, back off!
Well, actually, that will happen whether the ejector is in place or not. Either way, back off!
It sure won't hurt anything to leave it out but if you are planning to true the bolt face installing a clearance fit pin that is a wee bit proud of the bolt face before it is trued sure makes for a nicer looking job. If you ever want to go back to the ejector, remove the retaining pin, give the bolt nose a few whacks on a piece of plastic and the pin should pop right out.