It doesn't look like most of the chassis is within a few millimetres of level, but there's a definite crease running through the front end.

I reckon I'll flip it over, weight 3/4 of the chassis down and jack up the bit that's bent. Once there's some force applied, I'll heat up the bent bits and hopefully it'll ease back into roughly the right shape.

If that doesn't work, I'll take some of Clarkson's advice.