jturboawd

This probilly seams rather trivial, But I have a carberated 400-450 horse sbc, ratehr large cam, 4 barrel holley 750, with all the typical bolt ons. But it is only 9-1 compression. I have read the book on timing, asked many people and always get contradicting advice. Oh, I also have a 150-250 wet shot set up. How should I time this. Oh its vacume activated advance. What methods, and or what timing should I give it. Please what proceedure would you take in timing this....
So far I cant seem to get it just right. Mabee because the compression so low.
thanks for any input