Thank you to all for your comments - I will send a general note here as there are quite a few replies needed.
All of the discussions got me thinking. I went down to the workshop and measured the chainring and it turns out that it is 1/8" and not 3/32" as I had been informed by the seller. I had not thought to check this until now. The freewheel I will be using, for now, is a Shimano BMX Model SF-MX30 17T which is apparently compatible with both a 1/8" and 3/32" chain (or so it says on the box).
So it looks like it will be a 1/8" chain after all. I am not going to be using a period chain but will look for something which is not too flashy for this classic beauty! Any recommendations?
Ottawa, ON, Canada