Old school guys always said,once you do the 30 minute or so break-in, change
oil/filter after the engine cools down. Then get it up to temp and go on the open road, 3rd gear,go from say 2000 rpms to 5000prms with your right foot to the floor, then back off the gas and let it "coast down to 2000rpms, do this 10 times and your good to go.....
Did pretty much this with my 351-W built back in the mid 90's, still running as strong as ever today..........
David