Please please please do not do this. The cryptosystem which Bitcoin keys and addresses are part of assumes for its security that its private keys are uniformly random numbers. Flipping coins by hand will definitely not give uniformly random numbers, and is probably so biased (depending on your hand, the coin, what side you pick it up from, the surface it lands on, etc, etc) that you can measure it yourself by just flipping a coin and counting the zeroes and ones.

If you swap out one component of a cryptosystem for another you have constructed a new cryptosystem and need to argue its security. And I guarantee you won't find a good security argument for "Bitcoin script with biased randomness".

To add to the presumption of insecurity that should be applied to all new cryptosystems, let me point out that much of this one is gibberish:

So there are 2^160 public keys but only 2^96 private keys? Ho does that add up?
Are there private keys than unlock more than one public key?