Originally Posted by daverup

I've used the SRAM 8 speed chains on a couple of helicomatic freewheels. The gears are different than the more common Shimano or Suntour clusters, and may not engage as smoothly. The teeth of the helicomatic gears are not beveled or ramped like most others. I've never used a KMC chain on these, so I can't tell you whether or not that is an issue.
You will probably hear others advice on the need to change out these hubs for better designed models. The earlier helicomatic hubs have a long history of bearing failures, which might be attributed to the small bearings in the rear hubs. They also don't do a good job of keeping dust out of the bearings which contributes to problems. If you decide to keep them, I'd make sure you rebuild them after a thorough cleaning. Inspect the cups and cones for signs of bearing failure and use new grade 25 or better replacement balls.