The 400 appeared in several variations over the years, so it all depends on which version you have. According to the specs, the original, standard 400 had a capacity and maximum cog size of 28T, so it should handle the gearing, provided you do not not have a differential of more than 12T on the chainrings. However, it was listed as only having 5 speed capacity, so it may not have sufficient throw for 6/7 speeds. Often, the advertised specs were somewhat conservative, so it may still work, despite the official claims. Later versions had equal or greater capacities in terms chain wrap, maiximum cog size and throw.