I see a model A gastank trimmed out in a posting here... for those that are going to cut one, the baffle flanges are soldered to the front, back and bottom of the tank ... The top 1" or so is clear all the way around the tank, no baffles... that is where I try and cut... makes for a relatively easy job... But to leave the dash face entact is a different animal... Be prepared to cut small pieces from the bottom only to run into soldered baffle flanges along the way, helps if you know where the baffles are, even then you will need to cut a hole just to trim a baffle flange from the dash face... So when you see a gutted tank with the face entact know it was a liittle tougher than a 1" from the top tank cut ... Pic is of an A tank top with '32 cowlvent installed, note the tank cut at about 1" all around... but I usually like to leave 3 or 4 semi circle tabs hanging down, drill a hole and later hang a wiring harness, defrost ductwork, rear of a glovebox or speakers ETC... My A tanks are out on the back 40 and with another 18" of fresh snow... more pix later...
Here's a picture-heavy thread showing how I did my '28 Tudor tank. Hope this helps. http://www.jalopyjournal.com/forum/threads/28-tudor-highboy-sitrep-1.222387/
mine was done similar but a while's back and rough , new panel inserted later where the tank was cut for carb clearance, its tidier now but I left the rough cutting there , part of its history
If you try and cut the bottom off you will find the baffle are soldered everywhere... you cut holes just to find the solder... i cut 20 holes or so... . To save the tank's face / front you "will" have to cut all the little holes... . BUT, henry soldered these baffles in the bottom half of the tank before he welded the tops on... So if you cut about 1.25" from the top you won't need to cut any baffles... in comparison, not a bad job. . pay attention to the gas gauge glass, very few were magnifying glass, save those...
Here is how I did my Model A. Uses a 32 style Fiberglass dash panel. The 1st pic shows the mess of how it was cut from the previous owner and I just cut out around the perimeter. I think they used a axe and tin snips. The tab on the left is where I mounted the headlight switch so it pulls downward instead of on the dash pulling outward.