Yes, take a look at some car ESCs. Good luck! :)
Of course, most all rc car and truck brushless ESCs'. Setting it up to do that will most likely require that you arm the motors in neutral. Changes will have to be made in the code though. You need to set the code up to only read proper throttle PWM when you want to initialize reverse. But what blades are you planning on using to do this with? Also, think about the amount of centrifugal force generated by your props. When you plan on reversing this you may find that the motors will seize and fail considering they are direct drive. To effectively fly upside down like you want a variable pitch system would yield better results. I have experimented with this, before.
It is very possible to connect a tail blade assembly straight to the "extended" shaft of a high torque outrunner. You will have to have a either one servo per each motor (if pitch system is to control attitude as well), or one servo that changes the pitch of all blades proportionately (this only to change thrust vector). Both methods will require you to manipulate FC setting from what they are, and you will not be able to do this with just any FCB. The system will also consume much more current.
Spend more time looking into making a system that runs off of one motor and servos for each head. Torque drive is your best bet. Metal torque drive gears preferable. Over sized tail blades, low RPM. As far as the prop direction, it should stay the same as your fixed pitch system. To achieve this you will need to invert some of your primary torque drive gears. All the parts are readily available. Can be done, but will require some work.