Welcome to the forum and congratulations on using your 28 for competition shooting.
For my money, your best options are the Safariland speed loader, designated N1, or an SL Variant spring loaded speed loader. The bad news is the the Safariland has not been made for several years, and I'm not sure the Variant is still available, either.
The good news is that if you can find some on ebay, or Gunbroker, is that they will probably still work fine. I have been using the same ones for over 30 years and dropped them on concrete when I was shooting PPC and they still work and look like the day I bought them. The Variant's are well made and probably easier to handle and maybe faster than the Safariland N1. Safariland never made a Comp ll or Comp lll for the 27/28 Smiths.
I have used HKS and Dades and neither are as fast or as secure as the Safariland.