I am gravely confused unless you secretly added a built motor, single turbo and an extra 300hp to your "Comp Gee".
Either way, challenge accepted this spring.
IIRC Audi says that the tires must be within 4/32nd of each other.
I'd have him read his manual, if it's the same brand/size of tire, i'd say it would probably be just fine.
Then get a LS1... Just about everybody who I've known who had one, loved it.
Put snow tires on it and get a manual, dear god please get a manual. You'll have fun with it and it will be reliable.
I think a GTO is a great idea, I'd hold out for a LS2 model though.
We know you don't have any issues pedalling RWD cars in the snow, so go for it. The rest of the year you'll be glad you didn't get the legacy.