Don't think it's a 427 Vette, it's a 327.
Did u had a chance to tweack the car settings? In GTL, all the cars come "preset" with a HUGE understeer tendancy, to help newbies drive around.
The problem with that is off course that the car will not be able to make the car take a turn fast. When u tweack the settings so you can actually turn, then you end up having to ride the throttle and work your steering wheel.
The vette has this big heavy engine in the nose compare to his "lightweight", so she is fairly reluctant to start a turn. In GTL, the best way is to force the car in a little oversteer and ride the wheel/throttle to keep the nose inside the turn. Doing so, you should burst out of the turn already full throttle, giving you a starting edge on the straight where you overpower anyone.
In a nutshell, the cars are easy to drive till you have to push to go faster than the guy next to you.
Here is what
Doug Arnao, three time SCCA champion has to say about the Vette:
“Classic American Iron. It’s easy to see why this is a favorite car in the vintage race
series. With legendary Chevy small-block V-8 power, it drives predictably and gives a
sense of confi dence in its handling.
To be truly fast with this car it must be pushed it into a slide in most corners. It
will rotate around its center which makes it easily balanced with the throttle. The
technique is to enter the corner fast enough to get its tail out almost immediately
- then be feeding the throttle on as you turn in. Back the throttle off just enough to
keep a slight sideways attitude past the apex. When the exit is in sight you can feed
more throttle to sway the rear end out just a bit more and balance that out to the exit.
Tight corners use much less throttle and use more pure steering. It still fairly nimble
for a heavy car as its near 50/50 weight balance, low center of gravity, and fully
independent suspension allow the Corvette sportscar like handling.”And here's the Vette Characteristics:
Weight:
1325kg (with driver) "Definitly not FunkedUp driving"

Weight Distribution % F/R:
52/48 no fuel
Engine:
Chevy 327 V-8
430hp @6200 RPM
550NM Torque @ 4000
Transmission:
4 speed
Aerodynamics:
Lift @ 100mph: 0N
Drag @ 100mph: 927N
Tires:
Dunlop Vintage Treaded.
Front: 5.50M-15
Rear: 6.00M-15
Chassis:
Lateral Inertia: 1580kg/m2
CG Height from ground: 490mm
Drive train layout:
Front Engine/Front trans
Rear wheel drive
Suspension:
Front: Unequal length Upper/lower control arms
Rear: Independent rear trailing arms w/ lateral link