Just my opinion —-but if you want a Cadillac you can drive in reasonable condition I do not think that will happen with a convertible or a Fleetwood ( higher end models ) but could be doable in one of the sedan models possibly
The price you are suggesting might be doable if the Cadillac needs —-a real real lot of work —to bring it back to being road worthy
The latter option might be possible but little chance in the convertible model with AC which is the model of my own choice in these years
Miracles do happen as we know
Good luck in your Quest !