Rusty floor pan!

since our cars are uni-body and the front floor pans are connected to the frame rails and trans. crossmember i would insist on welding them in. if i were you i would get the floor cut out and cleaned up. get the patch where it fits nice and neat then take it down to the loca exhaust shop and pay the guy $50-100 to weld it up for you. you could drill holes and use sheet metal screws to hold it in place while you drive it up there. space them every inch or so. then when you get there take everyother one out and have him weld the holes up. then take the remainders out and weld those up. then have him stitch weld it from the bottom. about 1-2" welds spaced out a couple inchs. then along the frame rail and cross member .