Do you mean the nickle content of the aluminum alloy engine case, or do you mean having a nickle liner on the piston sleeve? If you mean the sleeve, I've got news for ya'. Nickle plating isn't worth a dang in such an application, it's crome alloy that you want in there not nickle.
I cannot tell you how many times, and engines, that I have seen that are not too used that have the nickle flaking off - this is really bad news and will destroy the engine on all levels.
The 'cheapo' (Chinese made) engines I have actually have been better performers than some of the higher end engines (Japan production).
Perhaps I am bised since GMS.47s only cost me 50 bucks; ST .61 Ringed 55 bucks from a local friend. Even if I had to pay the marjed down retail it would still be worth it to me.