Re: MT60
Mr fromage is completely correct. There is a lot of talk of "speed capacity" of mechs. In the main It's just not true. Think about it.....its just a big spring pulled and released by a cable. The distance it moves comes from the shifters, so you do need those to be compatible with your chosen freewheel in terms of cog spacing.
Mt60 are great mechs, made in the days when shimano engineered stuff to last.
Enjoy.