Tell me about freewheel cog spacing vs. chain width.

I finally got the freewheel off the rear wheel of the tandem I'm rebuilding. It's a Maeda 6-speed, one of those narrow-spaced freewheels only slightly wider than a normal 5-speed.

My recollection from back in the early 80's (until recently the last time I paid serious attention to bike parts) is that when 6- and 7-speeds first came out "they" offered narrow freewheels to allow 6-speed upgrades on 5-speed (120mm) bikes, and 7-speed upgrades on 6-speed (126mm) bikes. But these narrow freewheels required a special chain, perhaps called Ultra or some such marketing nonsense. Both the '82 and '83 Peugeot catalogs listed a Normandy 5-speed for the TH8, so the 6-speed upgrade would seem to be one of these narrow varieties.

Now, I could simply continue to use this narrow 6-speed (even though I'd rather change the gearing). But for yucks I checked it against the new PC-870 chain on my Raleigh. It looks like the chain is too wide for those cog spacings.

As an experiment I tried mounting my Raleigh's the new 6-speed (126mm) Shimano freewheel on the tandem hub, then putting it on the bike. It looks like the freewheel will be too close to the stays for shifting onto the small sprocket.

So I have two options, find a narrow chain or go to a 5-speed freewheel. I like the looks and so far am impressed by the shifting performance of the PC-870. So I'll probably go with a new IRD 5-speed, probably the 13-28, or 13-32 if I felt like stretching the RD to its limits.

So here's the point. Do I recall the freewheel/chain width issue correctly? Would any of you recommend a narrow chain? I would suspect a narrow chain might wear faster. Also since I'll be needing to create custom-length chains for both sides, it might be more cost-effective to chop several standard chains whose left and right sides can be mixed-and-matched.

As always, thank!