Here are some pics that may help:
We have had some feedback from a few customers that their clutch MC bracket (that sandwiches between the firewall and the brake booster) has not lined up 100%, with us finding that the hole size was a bit small (the large hole in the clutch master bracket where the booster passes through). If the entire hole was larger, there wouldn't be an issue. We suggest you clearance grind the clutch MC bracket just enough to clear the cast iron tail of the hydraulic brake assist unit and everything will come together. You may also buzz a small amount out of the tail of the brake unit casting too (1/8" max). We purposely run the brake unit mounting centerline up higher within the bolt pattern and firewall pass through hole to accomodate a 6 degree upward installed brake unit angle, and this raised centerline keeps the brake pedal rod angle proper.