I have also created the same set up, 7 speed freewheel (Shimano MF-TZ21), Athena 8 speed ergo shifters and mech. Doesn't line up for me, the mech moves too far, if it is aligned on cog 1, by cog 5 it is seriously rattling, cog 6 jumps up to 7. Even bought a second mech as the first one I bought...