Hi BR...
Your Battenkill isn't really "overweight" for your TFO, especially since you don't
have to fill it clear to the brim with backing.
The BP 270 (at 6.4oz.) is about 2 oz. heavier than anything I personally would put on a 5-wgt. but -
you may like it - and it isn't likely to hurt anything.
My advice is: Put your equipment together and go fishing!
Best,
5/0