Thanks for the comments. The engine was dynoed before I bought it. At that time they reported just under 600 hp and 600 lb-ft of torque at 5400 rpm. I wasn't there but I thought the guy I bought the engine from was honest. I did meet the guys at the shop where the dyno runs were done and I had the impression they were good.
There is a shop in northeast Philly that has a chassis dyno and I have gone there before. In fact they dynoed the car when the 383 was in it, but that's a story for another time. Today they made the first pass and had 500 lb-ft of torque and about 420 hp and were running rich. They worked the air bleeds a bit, reset the timing which was too advanced (I guess I'm guilty but I don't know how.), made a second run and got an additional 25 lb-ft of torque and 25 hp. The a/f ratio was good. Final numbers are 446 hp max and 527 lb-ft torque. Then they put up a different screen on the computer to check cruise speed which also looked good. At that point he said I am done, eveything was good. I guess the guys with the engine dyno had dialed in the carbs. He said that he figured he would have to spend 2-3 hours messing with the carbs but they were spot on. So only two runs and about $160. A lot cheaper than the last run on the 383 in which they spent about 4 hours trying to get it to run well.