I have a 66 and a 67 Lincoln - the stock motor is a 462 MEL motor that was only manufactured for that particular car. It has no interchangeable parts with the 460, unless you do some intake work to swap carbs. The motor is 340 horsepower and 500 ft lbs stock, which is more than enough when you consider the brakes for that car.
If you start looking at swaps, it's going to be pricey, because you will also have to swap the transmission - the C6 that came with the car is an early C6 and it won't bolt properly to a 460 which is the only motor you will find to make more power at a reasonable price. Stick with the motor that is in there, and remember, it's not a race car.
If you have any Lincoln questions, don't be afraid to ask.