Lenght of antenna cable help

Hello,
first time posting, hoping to get some answers. any help is greatly appreciated.
After email the company, but did not get any good answer from them. i believe this is the last place to get some help.

Basically, I have 2 8dbi outdoor omni directional antenna. one for the access point and one for the brigde. The distance between the access point and the bridge is around 400ft. (a block away, straight line of sight).Right now, because of the antenna cable lenght, i have to put the access point and the bridge up in the attic. The antennas are mount on the ridge of the house, close to the roof. I want to move the access point away from the attic.
the distance from the mounted antenna is 30ft away from the room where i want to put the bridge. And the distance for access point antenna to the access point itself is 50ft away.
My questions are, if i use a longer antenna cable .. a 30ft for the bridge and a 50ft for the access point. Will that work? i know that with a 50ft cable, you loose 3.3dbi. Will that dbi lost have any effect on my internet connection?
I just want to know that it works before i buy the cable. I know that i have to buy the adapter/pigtail for the cable to be able to fit into the access.bridge point.
The cable i m looking at is a LMR 400 with n-type male to N-type female.

Thank you.

Blnkcruiser