I don’t think that poly is much use these days, I would zero in on poly~ as my approach. I have an example you might want to look at: Simple FM Synth which can be found here: http://www.xfade.com/max/SFM/

It also has a pair of synthesis types, and is managed with poly~

Your synth appears to be completed – making the whole thing polyphonic would require some work, as I believe that a polyphonic synth in Max needs to be approached as such from the very outset. But take heart! The [poly~] object is your friend. Identify first which parameters you wish to control from the top level. Will the filters be top level, or inside the [poly~]? I’m guessing the only thing you want to ‘target’ individually is the oscillators’ frequencies and amplitude-envelopes so use the [target $1] message to [poly~]. Most of the other paramters you wish to control could be applied using the [target 0] (all voices) message. Remember that by default numbers go to specific voices, signals go to all. Look in the Cycling74/example folder for the synths that live there for more pointers

HTH
Brendan