1969 Nova widest front tire and cutting inner fender?

[Moabdude]

I have a 69 Nova and want to put Airride on it. I want to put 18" wheels on it and 315 in the rear.
In the rear its no problem but how about in the front?

What is the widest tire in the front with a stock subframe and what size rim and what back space do I need.
I have ATS spindles, C5 rotors and C5 calipers.

Also if I put the Airride in the lowest position, do I need to cut the inner fenders (I did that with my 68 Camaro).
It seems like the wheels are going to hit the most outside part of th inner fender?
Anyone experienced?

Thanks
Bram