The mounting block bolts can be removed, and the body of the starter may need turned/rotated from the default position to clear engine block, headers, etc. This feature is by design. Make this adjustment to add clearance as needed. Also It is extremely common to require a starter shim to achieve proper ring gear engagement. If ring gear is too tight to starter teeth, Shim as needed. Shims are readily available at local auto parts stores. Customers responsibility to shim as needed.