There is no "Overspeed" warning on the P-Model (P-35) Bonanza. Any warning would be characterized by the sights and sounds from your pilot's seat as compared to those sights and sound during your bird's normal operation. But, don't disregard these. You are doing the right thing by investigating these.
I happen to own a rare copy of the original 1961 publication of the P-35 Model Owner's Manual. The information contained within is quite a difference from the information contained in the current publication. That said, there are two audible warnings (other than the Angle of Attach, or Stall warning). These are:
1. The aforementioned throttle setting at approximately 12" MP with gear up and locked.
2). Gear switch engerized to the "Up" position with the gear safety switch (squat switch) open (requiring gear struts to be depressed).
The only possibilities that the first was causal is that the proximity switch has moved (on the throttle shaft). Not likely but, worth having checked by your AI. Or, your throttle position was at or near the setting commensurate with 12" MP thereby energizing the proximty switch.
Although, neither of these were likely characteristic of the circumstances during your high speed descent. They are worth having your AI investigate.
However, once yoiu eliminate these two as sources of warnings, let's now look at the stall horn warning as a possible source of audible warning. We should be clear that there is no relationship between the stall warning system and the airspeed indicator/system. The stall warning is simply an indicator of your bird's approaching its critical angle of attack. This is that mechanical switch located near the leading edge of your left wing. Energizing this switch would not be likely in the high speed descent that you descibed (which is really not high speed circumstance and well within the normal operating speed range).
If the circumstances were as you described, I would look for sources of audible sound other than these warnings. Perhaps perhaps even a gear door being slightly open causing the audible sound similar to that which you described. I would recommend that you have a recommended Beech AI look at your landing gear system (or better yet, attend the ABS service clinic). The landing gear is one of the systems on which they focus a fair amount of time and attention. If convinced that this is not the source, have your AI look for other sources of sound generators similar to the landing gear system. The landing gear system's geometry and tensions are checked out (measured) thoroughly.
Of course the by-product of attending the ABS Service Clinic is that the attending AI can recommend other possible sources of sound which you descibe to him. These clinics are intended to be very interactive so that you, the owner operator, can better understand the mechanical health of your airplane while appreciating the requirement for regular scheduled maintenance.
In my humble opinion, neither the stall warning system nor your gear warning system seem to be the logical sources.
All the best.