timing for 285 horse good wrench crate motor

[diggerbob]

about 15 years ago, I bought a 285 hp, 350 crate motor at a chevy dealer and put it in my truck. I didn't get any documentation with it at the time other than a single page that gave a few key specs ( it is 8.8 to 1 compression). I put a HEI in it and set the timing at 10 degress @ 800 rpm which is what the one page spec sheet said to do.

At high way speeds, I can hear a little knocking so I think I may be getting too much advance at wide open throttle. The specs for 330 hp engine that gm makes today says that this engine should be at 32 degrees at WOT (vacuum plus centrifugal advance) and the specs for the 290 hp engine also says 32 degrees at WOT but using centrifugal advance only. My question: Do I need a vacuum advance on my engine or should I just go with the centrifugal only? I am going to have my mechanic buddy recurve my distributor if necessary to eliminate knocking but I thought I would see if anyone here knows about this crate motor and whether or not is was designed for centrifugal plus vacuum advance or just centrifugal...