Help! I bit off more than I can chew! Body work

No one mentioned restoring the corrosion protection! If you are replacing metal you will need to apply a zinc coating called "weld-through primer". Just a couple thin coats to all bare surfaces. You will still be able to see thru it! This should be done before any welding is done. When you weld these pieces together the zinc will melt back into the metal and restore its corrosion properties. I remove the lead and welded up all of the factory seams and filled with "Allmetal" filler that has aluminum in it. Be sure not to apply to much cause once hardened it is very hard to sand. Once this is done apply a coat of "metal glaze" from evercoat. This is excellent due to it having adhesives in it rather than sticking to just scratches in the surface. NO BONDO!! That **** will shrink and pop off over time. After you final sand the metal glaze if there is a large area of bare metal you will need to apply an acid etch primer first. Just 2 thin coats to bare metal only that you will still be able to see thru! Once that has flashed apply filler primer and final sand. You will need to use a good sealer first then you can apply the color coat then the clearcoat. If you use seamsealer be sure NOT to use 3m fast & firm, it will haunt you later!! Get a good 2 part seamsealer from IES. Most bodyshop supply stores carry good products and can advise you of what you might need. This is coming from a Master collision and refinish tech(Retired). After all this has been completed be sure to apply some undercoat to the backside of the repair to keep moisture from ruining the repair you have just completed. GOOD LUCK!! I have done this thousands of times over the years.