If you are trynig to get 6 speed indexed shifting working with a Suntour freewheel, and Shimano shifters there is your problem right there. Suntour and Shimano indexed systems were spaced differently, and the parts are not supposed to be interchangeable.

The Uniglide DA cassette on my Razesa shifts pretty damn sweet, it's hard to imagine Hyperglide would be a lot better, but I'll find out when I upgrade it to 9-speed. the freehub body is in the mail.