Timing and ignition specs

I own a 1963 adams skier, with the interceptor v8, and have been having little luck finding anyone around here (Wisconsin), who has the correct specs to set the timing. Had a problem last summer with the boat bogging down under load. Had a boat dealer replace the points, has new plugs and wires, distributor and coil, but havent been able to try it since. Dealer said he couldn't find the specs to set timing. Fires up and sounds great on land. And it ran fine , turned it off went to go again, and it bogged, not going above 2100rpm. Any help or ideas would be great!! thanks.
     Also any infomation on where I can get parts for the motor would help also. I believe my dad said it is a 290?

This fellow wrote an interesting article about setting timing in general:

http://members.aol.com/dvandrews/timing.htm

Talked to my dad today, and he said it is a 256 Interceptor motor. Also was thinking of posting some pictures, he would like to see if there is interest in anyone purchasing the boat. We have refinished it twice in the past 10 years.

If it bogs down, sounds like the timing is too high and when it advances it is sending fire to the wrong cylinder. When I bought mine, it ran perfect, but after say 1/4 mile above 3,000 rpms it would make a slowing down sound and die with a cough through the carb. I had the distributor pulled off and check on a machine, and it was perfect. The guy popped it back in, he told me to rev it to 3,000 and he set it while it was running with a timing light and backed it down to idle, and the timing was set a 4 degrees. Then it ran perfect, give it the gas in neutral and the whole boat will rock. That was for a interceptor V8 260.