Spacer for HS-12 Sumiko headshell

I need some ideas and sources for a good, non- magnetic spacer to use with Shelter 501 MK II, mounted on Sumiko HS 12 headshell.
I feel Technics VTA adjustment is not low enough even at the lowest setting, and using SDS Isoplat mat with cork backing.
How does the Shelter work with the Technics? I considered that cart but decided to go cheap and bought the Denon DL160 with Sumiko headshell.
It works very well, just need to use auxill. counterweight.
i'm also using SDS Isoplat mat and Audiopoints.