I googled "pirate metal detector board" expecting to find nothing, but lo and behold -- it's on ebay -- a pulse induction board for $35. It says to use a coil of 0.7 mm wire, 21 turns, diameter of 28cm.
Using anything else your results will probably be bad, but for the sake of experimentation... 28 x pi x 21 = 1847cm. Online wire calculator says 1847cm of 0.7 copper wire should have a resistance of 0.805 ohms.
There are probably online tools to calculate the inductance (mH) of the coil they described, and if you have the right meter, you could measure the mH of your chinese coils. Capacitance probably plays a role, too.
I don't know what happens if the ohms or mH are mis-matched. I don't know if you will mess up the board, or if it just won't detect well.
Perhaps you should build the coil they recommend, see if the resulting metal detector works at all, and if the results are acceptable, THEN risk hooking it up to your chinese coil and see how it performs...
Good luck! Curious how well this board works. The seller claims:
Medium coin - 0.7 feet (20cm).
Soldier's steel helmet - 2 feet (50-60cm).
Large piece of metal - 4.6 feet (1.4 meters).