What head shell is a good match for the Nagaoka MP-500 cart on Technics 1200G

I repeat. What is wrong with the Technics headshell? My answer: nothing.

Not sure what caused it, but on on my SL 1200gr with the MP-500 there was a hum issue with every metal headshell that I tried (including the stock one). I tried a wooden headshell (bought on Amazon) and that solved it. Probably could have been solved with non-metallic screws instead.

I repeat. What is wrong with the Technics headshell? My answer: nothing.

I agree.

If you can find one, the Orsonic, (or AudioQuest version) is my favorite.

Orsonic made a series of headshells with different weights to suit cartridges with differences in compliance. The MP500 is probably not so well suited to the heaviest, which I think is the AV101. Also beware of poor quality copies of the AV101. 
The hum problem noted above could have been due to poor ground contact which is always a risk when you mate tonearm A to headshell B. Another reason to use the Technics headshell that comes with the TT. And it’s free!