Dear Marcel;
Leon's advice is sound because; Chevrolet had a 3spd. (with OD) in that era that 'bolts in' your car and shifts from the column too. The drive shaft may need to be shorter is all.
A 'stick shift' 63 Bell Air (rare today) will sell for MUCH more & faster than one with an auto trans, when the time comes.
For less than the cost of the conversion, a 70s era Nova could be bought with an 350 trans (from factory) installed, where the 'switch' is; easy, fast and cheap to do.
To do this in the Bell Air; you'll be spending a lot of money, to make your vehicle worth less and harder to sell later.
Good luck.
