Pulling a 318 and 904 together- advice please!

I'm not too concerned with them rusting from the inside. I did think about drilling a couple of small holes to let water drain if need be. With the back tires I have, I doubt the car will see any rain.

I didn't want to weld to the floor pans because of the flex. I know there are lots of differant opinions on this topic, but I thought my sub frames may flex at a differant rate than the body, and I didn't want break welds because of it. In my case, anything is better than nothing. I do plan on putting a bolt through on the front of both of my connectors, in case the weld were to break going down the road.