Tank options. Need a shorty not a sporty!

[Whiterabbit]

The DT100,125,175 tanks only hold 1.8 gal! At full throttle that won't get ya' too far.
But then again, who cares? Lots of gas n smoke stops.
FYI
76 up used the coffin tanks
100's &175's are 16.5 center to center of frt to rear mounts
125's are 17.75 c-c of frt to rear mounts.
So the main tank ends prior to the bend in the frame backbone for both of them and looked like some room for the coils, maybe.

 

[Phyberoptic]

Fixing to butcher the 74 bike and do the Monster brat kit. You lose the rear tank mount and the stocker would be too long anyways. Don't want to do the sportster tank thing. I saw a boxy xs400 tank and think it would be perfect if it is shorter than a standard tank. Are they??
What other Yamaha tanks kinda' sorta' fit with a little work. Mainly just need clearance for the coils and fit the front tank mounts?
Thanks for any ideas.

Here's the xs360/400 standard tank on an '80 XS650:

-=Phyber