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.

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!

Okay, thank you for the replies. I'm going to stick with the one that came with my turntable. I didn't realize it would be okay. I was worried it would be too heavy since I read where the MP500 was on the heavy side

According to the Internet, the weight of the MP 500 is 8 g. That’s middling as cartridges go. Also, I can find no specific information on the effective mass of the tone arm on the 1200 G. However, all sources say it is medium mass. So you have a middleweight cartridge and a medium mass tone arm. You should have no problems related to tonearm and cartridge incompatibility.