Fuel line and brake line bulkhead pass-through

[Doug1]

I need to get the fuel and brake lines through the back floor pan on my 2nd gen f-body. I have DSE sub-frame connectors welded in and the only way to keep them on the inside of the frame rail is to pass them through the rear floor pans. I will not have a back seat and the car is mostly built so this is a last minute change. My ideas was to take a 19" 3/4 pipe on each side and pass it though the floor, securing it with nuts on both sides of each entry and exit point. I'd use some sort of sealing washer as well. Alternatively I could weld it from the inside or outside as it passed through, though it might not look as clean as option 1. MY plan was to then route the lines through the pipes, keeping them out the cockpit in this manner.

Are there any disadvantages to doing this?