I installed the 67/8 skins on both of my doors... The came out ok, but between the new quarters and new fenders it's hard to tell which piece was off. I did end up welding filler rod to portions of the door edges and front fenders to get the gaps looking good.
Some of the rust on the doors went further than the skin so then had to repair that damage before re skinning. If I had to do it again, I think I might just look for repro doors. They are usually $300 each... Sometimes a little less.
Inspect the lower front of your doors before you get the skins, you migh find you have more damage than expected...
Jarrett try this link http://www.desertmustangs.com/1972coupe/Door_skin_repair/72-Door-skin.htm
I just did a 69 fb and it went well BUT!!! mark your door lines and on the bottom new skin BEFORE you perm install it. Take it off and mark a bottom line for the crease. They make some special pliers to fold the skin say 4" at a time, I HIGHLY recommend those or something else to bend a 90 degree bend at the bottom line (on the new skin) that you marked, so when you put the skin back on the existing bottom will fit right in the now perfect line on the bottom, then preceed to start all your folds. I hope this helps David