Rear Arch Fitting

[gus]

I have been looking at fitting my rear arches and can't decide what to do. If I set the bottom of the arches as made level with the bottom of the body work the wheels look lost. The gap above them is massive.

If I set a piece of 75mm timber on top of the tyre and rest the arch on it. The gap looks better, but I have 55mm of the arch below the body!!

I could cut the 55mm off, but wondered if anybody else has had this problem?
Just wondering what kind of clearance people had been leaving in their arches.

Cheers

Gus