Grinding, " diesel " noise under valve covers

So I'm gonna rip out the front area tile in a Hungry Howiez my Friend owns. He's also Always been a Mopar guy, and has had / built some bad rides. He still has a 71 Cuda 340, 4spd car. Had a 426 wedge in it, w/ a cage... he took it back to stock. Anyhow, gonna be doing 11 pm till when ever in the am at his shop. I should be able to get him by. I did start getting her ready to roll yesterday evening. Got a different dizzy in, timed er out. Ride height looks good, wanna double check both sides are the same before I lock down and torque stuff up. It's hard to get a super accurate # w/ a tape... I see the FSM show a wood ( looks like a folder) . I wish I knew where to get a slide rule...