And in terms of V8 swaps, has anybody swapped in the whole Corvette drivetrain? Meaning also the rear mounted gearbox etc?
As far as I know it has never been done. The modern V8 swaps typically use a front mounting T56 or T56 Magnum(TR6060). Some of the DIY builds and I believe some(if not all) of the Mallet cars reused the stock Aisin AR5. I highly doubt there is enough room in the rear so cutting the tunnel would be required I'm sure. Picture in link.
By the way, how is the chassis? Does it really ask for a more powerful engine? If you would choose a weakness with the cars, would it be the chassis, drivetrain or suspension?
In my opinion a GXP/Redline with a catless downpipe and a retune of the ECU offers enough power. That will get you to about as fast as a C6 LS2 vette but the power delivery is alot different in a turbo 4 than a V8. Me and most of the owners here would say that there really ins't a major performance issue with the car. It needs the slight bump in power that the aftermarket provides and some frame bracing with stiffer springs and shocks but just about any factory car needs those things. The chassis is a good design.
And looking at the Kappa chassis it looks quite similar to a Corvette chassis. Like a shorter version of the Corvette chassis. I think the Corvette started with this type of chassis after the Kappa?
But I would think most would say the Corvette chassis is better, even if just because it's a Corvette. But is it really? If so, what makes it better than the Kappa? I know the Corvette's is aluminum. But I mean in terms of performance and design apart from being lighter.
If you look a pictures of the Corvette frames you can tell the chassis design was already being used before the Kappa cars were even being thought about. The Kappa chassis looks like it was designed like the Corvette not the other way around.
The Corvette and the Kappa are similar both having a hydroformed frame and SLA double wishbone font and rear but to me you can't really compare the two. The Kappa was designed to be a lightweight FR roadster. It has a short wheel base, excellent handling, and enough power to get you by. The Corvette is a Grand Touring car. It is a little heavier, has a longer wheel base, and more power but still good handling.
The C5 and the C6 base and grand sport (LS2 and LS3) frame is made of steel. The C6 Z06 and ZR1 (LS7 and LS9) are aluminum but can only be had in a fixed roof to make up for the loss in stiffness. The C7(2014) does have an aluminum chassis but it was made 5 years after the Kappa stopped production so it is to new to be comparable.