drum to power disk swap what vacum pick up point to use for booster

Ive done the swap now just doing final work on it all i need a vacuum point for the booster
i have a CALI carb on my car sense thats were it came from only two vacuum points one small one for the dizzy and one large one witch is where the pcv is hooked up i was thinking if i tee into that would i have issues with blow back from the pcv to the booster
the book does not call any points out ether so im asking the others for help

thanks