http://www.chuckhawks.com/recoil_table.htm
I know you've done the calculations already but i thought i'd post this recoil table anyway.
Shooting factory loads in all 3 calibers from identical wieght rifles the 270 will kick slighty less,so slightly i don't think you'll notice unless you move up to 180g in the 30-06.
If less recoil is factor in the back of your mind why not look @ something like the 25-06,6.5x55,260,7mm08,308?
If i was building or buying a light wieght rifle i think i would opt for a short action.......but that is just me.
Good luck with the build