I'm rebuilding a 396. I honed all the cylinder walls and they look good except one. There is a very,very,very small nick at the very top of the cylinder.
Should I worry about it. It looks to be above all the piston rings.

If it is above the ring, you should be fine. I would run it if was mine.:yes:

It's right on bottom of the ridge build up area of the cylinder.

You won't even notice the scratch. Run it.

However, if the ridge is bigger than say, .005, I would consider getting it bored anyway. The amount of ridge you have is how much your cylender has "bored" itself by normal wear over the years. The larger cylender size is decreasing the tension on your rings, and even new ones, will let compression out and oil in.

Ya' gotta bore gauge handy? You wouldn't put .030 over pistons in a .040 over bore, don't leave the stock pistons in it if you have anything approaching .010 of wear.

Like the guys above said, its not going to hurt, bigger question is how big is the bore.
I spent a few years in an automotive machine shop working for a very savy guy. He always stopped honing just before it was clean, he called it a "witness mark!" When ask what he meant, this is witness to the fact that I did not take more meat out of your block than was needed to clean the bore. Or put the other way, if he honed it clean the customer always bitched that you made it too big!

There was no ridge to remove.

I honed all the cylinder walls slightly.

Thanks for the help.