What car do you want to put the Caddy motor into? It fits into quite a few with minor "Do it your self" mods.
Someone mentioned a Camaro. A 70'-81' Camaro or Firebird would be a good choice. They come with an 8.5" 10 bolt rear that will take the Caddy torque without problems. Two small steel plates welded to the front of the cross member will allow the stock CDV mounts to be used. You will have steering shaft clearance problems that can be fixed by unbolting the column from the firewall and moving it as far to the driver side as possible. You then redrill holes to bolt it back down. Your main expence will be making an oil pan, or finding an Eldo pan with a rear sump.(I am assuming your car is a Coupe DeVille). The CDV manifolds will work. The right side will be tight against the front of the upper A-frame. You can use a 77'-79' 425 manifold that has a dimple to clear. The 425 manifold is a little more restrictive though. Headers on the stock motor will only net you 10 or 12 HP. More as the motor gets built up with speed parts.
In stock trim, your motor will make around 300 HP on a dyno. Stock compression is rated 8.2-1 with a 120cc head(Actual is around 7.9-1). A switch to a set of 425 heads, with 96cc chambers will give you 10-1 compression and a 45HP increase. The early 76cc heads found on 73' and older Cads will bump your compression to somewhere in the 12.5-1 range. Pontiac valves can be used in the 96 or 120cc heads. The 76cc heads use a longer valve. A 2.11" Pontiac intake valve will flow quite a bit more than a stock 2.000" Caddy valve. You can buy an Edelbrock Performer intake for around $250 or get nearly the same results from "Home Porting" your stock cast intake. An easy 25HP can be had by removing the webbing form under the carb and adding a 1" open spacer.
HotRod did a Junk Yard Jewel artical on the 500Cad.
Expect a mid 14 sec pass from your first outing. Once you figure out how to hook all the torque the Caddy has to offer, it will run 13's in stock trim with a 2.56 gear. With a cam, compression, and intake mods, you will be knocking on the 12 sec mark. With a 3.08 gear and a 200 shot of spray, low 11's should be expected. To go faster, one should think about forged pistons and rods to replace the stock cast Caddy parts. 10's would be asking a bit much of the stock bottom end......Wouldn't it? Dan