Ok, lets test your script without you revealing it to the public, just drop the first 2 characters on the left for this public key's private key :
03cefd304a9a8da40666e97b2d9650e31a71a9a9fcd29a24724d31a2fabbc8ea0e
Do you need the exact range or not? It has 32 characters and it starts with F, just drop the second character and give me the public key for it to verify, that could help a lot for others to believe you.
I did not understand your proposal very well regarding the range of your pk
but for example if you eliminate the first 2 digits of your pk in decimal and generate another pubkey you will possibly get a pubkey that starts (although I recommend explaining the range better):
1= 03941029...
2=02caf96e4..
After I know what your pubkey is, I get the rest of the digits.
without the need to generate millions of keys.