Changing 67 Fastback rear valance

Hello,

I need to change my rear valance for 2 reasons:

1) Dual exhaust cutouts
2) There was some damage that has been fixed before I bought it, but it would look better to have new metal.

The new valance came with purchase of the car, I need to get the exhaust finished up, TTI states start from the rear, so its time to tackle this. I've changed some floors out before, but nothing that will really be seen from looking at the car.

There's a ton of spot welds to cut out, also I would need to cut out and reinstall the support that is between trunklid and taillights.

I was thinking it might be easier to leave the top sill of the old valance and trim the new one and butt weld it together instead of removing and replacing so much.

Any tips? Suggestions?

Thanks,
Steve