i think you'll be fine but ya, 3.91's or steeper would be better.

Power brakes will work but realize your near the edge and if youre in traffic, a few pumps may get you. try a vacuum resevoir and you'll be fine. i run one like that and i just keep in my mind how much engine braking i do (it builds vacuum). I installed a vacuum gauge in my car so i know.

you'll like the cam. I like mine and mines 245/250. I want to go one step higher to a 250/260 or even a 260/265 but my compression is borderline (really below) what i should have for a bigger cam like that.

i mounted my vacuum can under the battery tray