Can the dealer cut keys from the vin on an 82 brat, or will i need to get the code from the lock cylinder?

If the cylinder is the original one to the car, they should be able to cut it as long as they still have the book/binder listing the key codes for each VIN. If they've tossed it...I'd suggest calling ahead and asking. In theory yes, in practice, who knows.

A good locksmith can also do the same.

The code will be on the passenger (right) side lock cylinder. If I remember correctly the code is the last 4 of the 5 digits or something close to that. As was stated above a good locksmith can make it happen.