Even though the postings are very old, thought I would throw a response in...there is a very good chance you have my old boat - I built the 502, had the trs drive beefed up, added the water-jacketed headers, added Bennett tabs, etc. etc...I sold it in 1998 to a guy in Gig Harbor, Washington...I have no idea what he did with it, but evidently ****ed it up quite a bit - the prop you are running is not even close to what a 7m Carrera needs - it might cavitate because it is so wrong - you might want to see if the old, custom prop is still available...
When I sold the boat (with a 850 Holley), it would top 80 mph - not by much, but definetly over 80 - the super narrow hull could handle absolutely any degree of rough water - the secret was to keep the boat level and on top of the water - just like the picture on the side shows...you need a prop that lifts...John Maazor in Fenton, Missouri did the one that was on the boat when I sold it...
The way you learn to do a hard corner is to set the tabs for proper trim and then let the drive out until top speed is reached - then with very small touches lower the drive as you turn - if you want, you can do just the opposite and set the trim before you set the tabs, but I always found it a little faster to do it the first way..
The boat was built in Miami in 1978 by Umberto Peron - hope you enjoy it!!!