In my opinion your best bet for cleaning out the pond and starting over is contacting a pond builder that is experienced in both new pond construction and rebuilding. For reclaiming an old pond you will be dollars far ahead if the builder has both a dozer and an excavator (compared to only having a dozer).
You can pump a pond that size (1.6 acres) dry with a three or four inch pump but it will take some time. As far as using a siphon that is only going to work down to a certain level unless you have a pretty good elevation drop lower than the bottom of your pond behind the dam. For a siphon to work the discharge has to be lower than the intake (I forget by how much but it is several feet). So likely best case is the siphon will get you maybe half way drained. Then it is down to a pump.
I would talk to the contractor and see which way they think it will be most economical. Depending on how your pond is laid out, if it is in a ravine it may be most economical to break the dam to provide an exit to push the muck through. If most of the muck has to be lifted out, an excavator is almost a must. Once a dozer gets on slimy muck they are down to pushing about a quarter blade full, especially up hill. Those steel tracks get slick on a muck covered bottom. For a dozer to have any pushing power they have to get down against a solid bottom and crowd the muck along one side of the cut. If you have both an excavator and dozer the dozer can push the muck mostly down hill to a point the excavator can scoop it up and throw it on the back side of the dam. This is the best case scenario. You are paying the cost of two machines running but they may be able to accomplish the job in a fraction of the time. Two large machines could get it done pretty quickly. One small dozer could be working on it for weeks. All the while worrying about rain coming and stopping the job in its tracks.
It may be better breaking the dam again, depending on the equipment available and the size of the equipment.
My experience mucking out and rebuilding an old pond 
