I work in a body shop.
with enough time and money anything can be fixed. the question is, IS IT FINANCIALLY VIABLE TO REPAIR IT.
if I can fix this car, your car is a piece of cake.
if you have a lien on the car, buying it back can be difficult. probably not in your case.
depending on the insurance co, buying the car can be difficult. sometimes the insurance co will make it extremely difficult to buy the car back. they do this because they can total it for less dollars because the car will have a really good salvage sale price. your GT500 will have a good salvage resale price.
state farm in my area makes it difficult to buy the car back no matter what type of car you have.
on what the insurance payoff will be.
if you didn't list the modifications to your car when you insured it and PAY EXTRA premiums for them. the insurance co will only pay out for a stock car.
if it's insured as a stock car you can legally remove the mods and return it back to stock before they take it.
insurance co's like to pick up totaled cars fast, usually the same or next day after they determine it's a total, because owners remove parts before they are picked up. they make extra efforts to pick up cars that aren't at one of their network shops, especially if it's a valuable car.
make sure your car is locked up INSIDE at your friends shop. they will tow it away ASAP after it's determined it's a total, even if they have to break the law to do so. it's a common practice in my area for tow truck drivers to cut chains so they can pick up cars. if they take the car, you call the cops. they will play dumb and say the made a mistake and there is nothing you can do to them.
once the car in their possession there is nothing you can do. when you try to get your car back, they will sell it fast and litigate later. and the insurance co will win 90% of the time. as soon as it's determined a total loss, it's legally their car in most areas. even before they pay you for it.
hope this info helps.
