A 150gr out of a .308 is very similar in ballistics to a 150gr out of a .270.
I wouldn't bother swapping them out, to be honest. I don't think there is a whole lot to gain.
Don't get me wrong, I love .270WIN but .308 is a fine round and has a MUCH larger selection of quality bullets...and the options of going HEAVY.
In .270 you're pretty much limited to 130gr and 150gr, with a choice or two in the 160gr range.