1967 Chevy Camaro breaking starters

First get yourself some new bolts, any parts store will have them, that rear bracket you refer to is there for 2 reasons starter support and as a heat sink, they're nice to have. What shape is the flywheel in?When you shim the starter install starter with no shims, take an 1/8 inch drill bit and check drive clearance between drive and fly wheel start with thin shims. Good Luck, Lou