My current "car project" is an 85 Eldorado FWD with many luxury appointments, such as:
Cabriolet/Soft-Top Look Roof
Power Brakes,Steering,Seets,Mirrors,Sunroof,Trunk
Sport Touring Suspension plus Level Ride
Engine: HT4100 V8 (130HP) "Digital Fuel Injection"

Pros:
Well, the options installed in this car make it great. Steering is Awesome, what you'd come to expect in a well-maintained Caddy! Suspension is upgraded, and worth it; the "Level Ride" feature is awesome. The feature stabilizes the rear wheels when cornering. The interior is just lovley, very padded and comfy. The moving seats are great too, makes the car acessible to many people. And of course that sporty-cruiser-caddy-sleek body style. That's why I love Eldo's so much, more different than many other caddy bodies in that era.

Cons:
While excluding the common problems in cars 20+ years old, they seem to hold up well with regular maintanence and cleaning. The biggest problem I can see in the car is the dreaded HT4100 V8 engine. This was Caddy's attempt to produce a fuel-efficient 8-cylinder engine, which is rather dumb, V6 would always be! The 4.1 engine is notorious for it's mis-matched engine components and severe underpower. 130 horses! This car is heavy, the last thing it need is a weak motor. Evan a 4.1 in PRIME condition is poo, so imagine one after 20 years of operation!!! Like I'm planning, switching the 4.1 for a 4.5, 4.6, etc. will cure this car of it's power diffencey. Once a powerplant worthy of Cadillac is power this car, you'll have one sweet cruiser...or maybe even a Sleeper!

All in all, I'd sayt the 82-85 Eldorados are one of Cadillac's best body and interior designs. As for the engine.....that's left up to you!