to restore or to mod

The vinyl was probably a lot more common then a 340 3 speed stick.

what condition is the car in? There are things that you can do to it an have no effect to valuation to the car and do other things that will detract in a major way. If it's future value is a factor in your decision. It is your car to do what you want with it. not giving much as to what your thoughts are as to what you want to do or what you're starting with...... I agree with squatch if your wanting to tub and cut up a decent 340 car it might be best to pass it off in exchange for a /6 car.