I started the floor lowering project > http://www.busconversions.com/bbs/index.php?topic=24673.msg325547#msg325547
My plan was to add a number of inches of insulation in the shell but this would result in an uncomfortably low ceiling and I did not want to raise the roof of the bus so I decided to lower the floor 8".
I know I am sacrificing some lower bay storage but it is the best solution for my use of the bus.
I am going to fabricate a new firewall. The original engine compartment firewall had a number of cracks , welds, and other repairs.
When I started stripping paint on the firewall I found a large number of bolt heads and rivet heads that were held on by nothing more than the paint.
Most of these were hidden stress failures and I am really glad I found them!