Suntour back in the 70's were a bit maverick, they played a wild card with the "Ultra" series of blocks / chains. they reduced the cog spacing from 5.5mm to 5mm so they could cram in more cogs on the freewheel and brought out a thinner chain..........just as rear spacing (OLD) went from 120 to 126mm which trashed their strategy. On top of that they had a haphazard "Ultra" range for the Winner and Pro Series so you never knew what was what.
There is a great history of Suntour on the net somewhere about their missed opportunities which (allegedly) were down to the boss at the time. They brought out the first slant pantograph and indexed gears IIRC.
8 speed gearing and chains uses 5.0mm spacing so should be OK with either the Ultra or 5.5mm spaced Suntur freewheels.
The reps who had to sell the stuff had a terrible time BITD.
Shaun