As mentioned before the cadillac power forum has a ton of useful information. Here's an index to some of their best posts which include engine swaps. http://www.cadillacpower.com/forum/index.php/topic,6984.0.html Here is a index to the links of the best cadillac websites: http://www.cadillacpower.com/forum/index.php/topic,6981.0.html I also read somewhere that the engines are all basically the same for power because the rating system changed during that time and torque figues. The small loss of power in later engines was due to a drop in the compression. I have a '76 500 I'm planning to put in a '40 Ford COE ramp bed car hauler.