I have a problem with my Holley 600 (4160)

Well, I changed the jets back to the 69's and I did the timing again. I set the initial/mechanical timing at 32 down from 35. I tried to set total timimg, mechanical+vacuum, to 50 as stated by Mopar Perf. but the set screw in the vacuum pot is down as low as it will go and total timing ended up at 52. The cars seems to run pretty good but I think the vacuum is putting too much advance and I can't get it out. Is there any way to adjust this in the Mopar Performance distributor? I am going to put the heat insulator spacer in this week. I will let all know how things are progressing. I think we are on the right track. Thanks for all the help. You guys are a world of knowledge.