I HAVE A 1993 CADILLAC DEVILLE IN GOOD CONDITION,THE CAR HAS 160.000 MILES ON IT. I'AM RESTORING THE CAR AND WOULD LIKE TO KNOW IF YOU CAN REBUILD THE 4.9 ON THIS CAR OR CAN I REPLACE IT WITH ANYOTHER ENGINE MADE BY GM ON THIS CAR? IF ANYONE CAN HELP PLEASE E-MAIL ME AT email@example.com.
The 4.9 just doesn't have the same power as the Northstar, and the deville is a heavy car. In your place I would do a compression test before any final decision about a tear down and rebuild. If compression is up to spec, a rebuild is likely to produce marginal improvements at best. If the cap, rotor, wires, and plugs are past their prime, a replacement of those could make a significant difference in performance and gas mileage.
You can rebuild the 4.9. A swap from a different Caddy year and model might involve some computer compatibility issues which would need to be addressed. I am unaware of any non-Caddy GM engines which are bolt-ins.
The engine being monuted as it is really jacks up your engine choices. Caprice guys have it easy. The 4.5, 4.6 northstar, and the 4.9 should all be fine. The northstar and some of the 4.9's might have compatibility issues. I'd say to keep it simple, stick with the same 4.9 as you have now. Yours being a '93, it has the most power. I know a few sites that sell remanufactured engines. I've seen all three of the engines listed for sale on that site. My 4.5 goes for like $1,500 I believe..? If you're doing a restoration...I'd say just stick with your existing platform. Unless you know how to rebuild and engine, it might be cheaper to just get a reman'd one.