Need suggestions on straightening a w123 euro bumper.

[winmutt]

I posted this on the Diesel forum :

So I took my bumper to get straightened this afternoon at lunch. They quoted me around $600. So. I went to Lowes and bought some 2x4 and C clamps and current have it all straightened in the clamps and said 2x4. It looks spot on straight (using the other side for comparison)

Now do I leave this on for a few days or do I need to counter bend? Could I put the 2x4 supported bumper in between 2 brick and stand on it (weigh 250lb) with a stoud friend or two to help? Remeber this this is only sheet metal thick.