How much tire to front fender clearance?

Hey all been awhile since I've been trashing around. Rented a shop and got the car out of another Natures workshop, so I have been far too busy building my car. So my question and details. How much clearance should I have as a minimum between the front tires and the fender lips? The car is a 71 Duster, wearing 245/40/17's on 17x8's with 4.5" backspace. Right now there is no engine or trans, and no torsion bars or shocks. It is sitting on a couple of blocks under the k-frame to mock up ride height. No my wheels aren't optimal, but o like them and it is the only option for now. My suspension is all Hotchkis, I bought it long enough ago that even the t-bars are Hotchkis. I don't remember the diameter, somewhere between 1.04-1.12, just not certain. So now it is a delicate balancing game between looking good, and being useable. The compromise is just shy of two fingers clearance between the inner lip and the tire. About 1.75" clearance. How much clearance do some of you have with your fat tires and stuff bars? Thanks.:burnout: