I went out to the garage a few minutes ago and measured all my 1-5/8 tubing and my 2 by 3 rectangle. I weighed a 5 ft section of the tubing it was roughly 10 pounds and the 2 by 3 was 3 pounds per foot.
I come up with a total of 262 pounds with all my cage and floor structure. I figure with replacing the floor with .024 and not having any interior in the car I probably gained 0 weight.