I am in the process of re-installing the original torsion bars back on my '70 Coronet. One of the torsion bars has a chip in it about 1/16" deep and 1/8" long. The shop manual says to replace, but i pulled it off like that. Do i need to replace it or is it safe to use the original one?

I'd replace them as a pair. It doesn't take much for one to fail. It isn't very pretty when one fails.

new ones are in the 200 to 300 range - its worth it - ever have one break?

lay your bar on a flat surface and measure in every direction-maybe draw a square on a flat concrete surface-4ft.X 4ft.and use a chalk box to mark the inside with 6 inch squares-use a carpenters square and a friend to lay out a perfect grid-measure height also-if your bar is not bent it's fine-only a skilled blacksmith can straighten a bent torsion bar

The nick is a stress riser.

I suggest replacement. The car is no fun to steer when the wheeel is tucked up in the fender.