smallblock project with my dad

I would tell them that I just put a motor in it and have no idea what it will run. Then do as Bomber said, couple of easy runs to get everything seated and then start running it harder. When you feel comfortable, drop the hammer and get ready to get shut down. Then you just say "I had no idea that it would run 10's" while trying to hide the smile. That's exactly what I'm gonna do.