Like I said, I hope your replacing the rotten metal, not just bogging it. Believe me, you'll want to replace it, there's a lot more rust in that car than you think. My old one had no visible signs of rust on the exterior, but it was diseased all through it. I'd suggest you pull the car apart completely and have it chemically dipped or blasted to remove all the crap so you can see where it all is and replace it, or at least spend the time and strip it right back yourself. ANd that includes all underneath it.
But then, that's just me thinking you're doing a complete rebuild and therefore building it to show quality, but you're not are you, it's a general tidy up to make it a daily right?