Warm the motor up and change the oil hot
If you change it more than you normally would like
1000 miles a couple times It will clean up
This also works on old engines you want to clean inside
Just change the oil a bunch
Oil's cheaper than diggin to it and it should be fine
BTW It's a good idea to change the oil several times in the first 3000 miles after a rebuild starting at 500 and going up....It doesn't cost much,you can look at the oil for junk.If there is crap in there ...It's gone!