Harmonic Balancer Removal ?!?

I have a 1980 280E M110 130K mi.

The waterpump finally let go, fortunately I was close to home. Star Motorcars only charged $25 for a factory replacement pump. Nice.

Here's the rub.
My harmonic balancer doesn't have an accessway cut into it. I'm sure it hasn't been off since it was first put on, so I hit the 6 6mm hex screws holding it in place with penetrant and came back to it the next day. They won't budge, even with an pneumatic impact wrench.
Here's the question.

Are the screws on the harmonic balancer reverse thread?

Thanks,
Stefan Stout