Don,
There are a couple of things to consider. A guy here has a 512CI, 600+ horsepower engine in his and it is quite street able. It will depend a lot on how the engine was built. Either way, you will need to be careful for awhile as that much power and torque can cause you to lose it easily. If you can, get the owner to take you for a ride in it and see how it feels. Also look for any heating problems in traffic. Find out what the idle is and what RPM range the power and torque come in at.
Hope this helps a little.
Ron
