Electrons in organic semiconductors (OSC) possess remarkably long spin relaxation times. Hybrid spintronic devices that combine OSC with ferromagnetic (FM) substrates are therefore expected to provide a route to devices with improved and new functionalities. A crucial role is played by the FM-OSC interface which governs the spin injection into the OSC. Using spin-resolved photoelectron spectroscopy and ab initio calculations we study here such possible injection channels in metal phthalocyanines (MPc). We report the first direct observation of the successful engineering of different spin-selective hybrid interface states at the Fermi level of a FM-OSC hybrid junction only by changing the central metal atom of a MPc. Our results demonstrate that tailoring the chemical interaction at the FM-OSC interface is a promising way to modify the spin injection channels and thus the spin injection capability.