67 dart front disc upgrade made..still not right

Bill and Mike, I'm using the 1 1/8" bore MC, although the info I'm getting on other related sites is conflicting as well as some suppliers websites. I'm going to go with the 1" bore MC. It's $50 but if it does the trick I'm all for it.

I did remove the booster and ran the rod in and out under vacuum and it followed but not quite as easily as i would have thought but having never done it before I'm not exactly sure how much resistance should be there. Also tried to run it in and out with no vacuum and it def won't move that way. Concluded booster is good.