Aftermarket peanut tank will not fit as a direct bolt-up. The new tanks have a "tunnel" welded to the tank, which fits the backbone.
I have a 2005-2006 carb tank at home I can measure the distance between the mounting holes for you if you need it, or just measure yours.
The issue will be mounting the EFI pump/filter in the tank.
“When the going gets weird, the weird turn professional....” ~ Hunter S. Thompson~
R.I.P. Rubberdown. 1971-2012
2005 E.G. Classic
Baisley Oil spring
Rinehart 3.5" pipes
S&S adj pushrods
3 stickers, adding 5 hp each. I swear......