Keeping the car stock will make it worth more money if its rare. But if u want to drive it instead of sitting around collecting dust i would do some upgrades to it. How many cars from the 30's do u see driving around in stock form? Im sure a 34 ford coupe would be worth alot more if it were stock. But how quick are u gonna look at that car and say thats a cool car. But modded with flashier paint and and custom body work and so on is gonna get ur attention to the car alot faster. I say do what u want with your car.

 

And at least you're not doing an STi swap OMG!!!1!

 

 

Which is exactly what I would do if it were mine.