you can do it with a voltage divider.
If your max is 7,2 why not use 7,5 instead of 8V for calculating the divider, increases accuracy.
And i think you should bring it down to 1.1V and not 1.3V. Your reference will be mapped as 0-1.1V/1024 for analog read.
About ATtiny, this looks promising:
http://hlt.media.mit.edu/?p=1695
Havent tried but would surely be nice and save a lot of money for simple projects