After reading other posts I have replaced my leaking stb fuel tank & will replace my port tank this fall.
You may view pictures of the process by copying & opening this link:
I highly recommend spending the time to prepare & protect your engine room & getting the best saws & blades as well as protective equipment. We used a very good Makita ( JR3070CT/Z ) anti vibration reciprocating saw & a Metal Devil circular saw: http://www.mkmorse.com/circular, this saw ripped thru the steel easily where it physically fit.
I built a false deck across the stringers between the engines with 2x6 boards & framed a box around the top, inboard & aft end of the stb engine. We then tented the entire stb side of the engine room in heavy plastic as well as 2 layers over the stb engine as well. It looked like an operating room but it made clean up much easier.
I ordered 2 smaller aluminum tanks (@ 180 gal each) to replace the original steel 500 gal tank. Florida Marine Tanks built both & they made the bottom tank with heavier walls to support the upper tank sitting on it.
Actual cutting time was @ 15 hours to cut into manageable pieces & about the same to install new tanks & plumb them.
Please feel free to contact me if you have any questions.
CINSUBAR II GB49 #36