Taking apart the floor/firewall seam

I did frame first. Be real careful how much you trim. I thought I was leaving at least an inch till I pushed it tight to the frame and it nearly slipped below the tunnel at the back corner. Once I had it close I vice gripped the front flange together and set a cinder block on it and crawled underneath. make sure you have contact everywhere needed - then drew the frame and all the edges on with a sharpie so I knew exactly what I had. Then I picked the high spots on the frame and drilled them next to my lines for my fill welds. A little more trimming and tack it in. Recheck and weld it.