I have used dozens of Tanks 11 gal 32 tanks over the years. I take the time to shape the side gussets and attach them so it looks stock. I've also used the 14 gal tank a couple times and have one on my new tudor highboy sedan. Some complain about the bottom but it's still the stock shape just 1 inch deeper.
Tanks like other have said , stock & 14, To consider for long Hwy rides or Less then 12 mpg , Vintique makes a 16 g , (I need one) The 3 Tank Inc brand I have had needed Trimming to fit , Detailing needed Especially if not using frame horn / tank covers To look Original