Need Little help - Mark Stuart Pulse induction Metal Detector 1

[adiputra]

Hi guys,

I need some help in making this metal detector.

IC2 - 40408 binary counter? what kind of this IC used in this project? i try to look out the net for its datasheet, i just found 4040B IC. Can i substitute this ic?
BFY407A diode - can i substitute this diode?
TLC 555 - also can i substitue this IC with NE555?
clock crystals 40 kilohertz - can i use 38 or 32 kilohertz?

if anyone in this forum can help me, i really appreciate it.

Thanks.