Manual-to-Power Brake conversion issues!

You are on the right path. From the factory power brake cars had a bracket that bolted to the firewall and the booster bolted to the end of the bracket. Unlike gm cars where the booster bolted directly to the firewall. You should be able to locate that bracket fairly easily I would think, check the classified section here or maybe even post an ad in the wanted section.

On a side note, have you installed the front disc setup yet? If so how did it work out and a part# would be awesome! Thanks