Changing 67 Fastback rear valance

Looks good Mat!

So, got the self tappers out, ran some in above the ribs, now my question is:

I want it to look correct, If I run more screws in above the ribs then weld that seam, the old ribs underneath are acting like a fulcrum and kinda mess with the pan where it connects with the quarter panels and spare tire well. Should I run all these screws in the middle of the ribs where the spot welds are, tack the bottom of the panel and then hammer the top in above the ribs?

Or, would it be best to start tacking from center out (kind of like torqueing head bolts) so that there is no "slack" that gets caught in the middle? Would have to weld the top 1st for that.

I don't know, I know I want it too look right.

I appreciate any input.

Thanks,
Steve