DYNAMITE
This is assuming the feeders are 120/240 1 phase 3 wire?
Without knowing if there is any space limitations, your best option would probably be:
600 Amp Main fused Disconnect > 600 amp splitter
install 4 x 200 amp fused disconnects off above splitter, wired from splitter to load side @ 200 amp and fuse for smaller units. (if upgrade on furnaces happen then it's only a fuse change
Then come off splitter distribution panel (you can use the tap rule to keep panel size down, so it dose not need to be 600 amp. i.e. depending on load and circuits required maybe a panel with 400 or 225 amp mains will be good)
