The Lancia and California will be the ones to watch, maybe the Viper as well.
But your R8 and Citroen GT times aren't what they could be (no offense).
The trick with those two cars, is to throw them into the corners as hard as you can and let them claw their way out. Sometimes you need a bit of a flick to get the car pointing in more, but a bit of oversteer in those cars goes a long way to better lap times.
A few examples would be the tight corners immediately before the bridge (from the start, there's a downhill run to T1, a left hander T2, another right for T3, and then you've got T4 and T5 before the bridge, and I'm talking about T4 and 5). Chuck those car in as fast and wide as you can, but make sure there's NO understeer at all. Use a flick or whatever to get the nose pointing in and then gun it out, it'll get you straighter through the apex of t4 and you won't even notice (hopefully) t5, and bam instant 15km/h faster exit speed onto the bridge.
. I'll probably take another shot with them when I start doing re-runs (the red cars in the chart) with your tips in mind 
in hour of the Grand Am Rolex 24 Hours of Daytona that takes place there. So far I've only done a sinlge car and it wasn't such a good lap. Will do better.
I'm pretty much at the same level as you. Average to quick, Milliseconds in it
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