These are just the answers to your questions to the best of my knowledge
Originally Posted by
County
Thanks for the responses.
Can I assume that a Shimano freewheel is English threading, as well?
Yes
I'm not too familiar with freewheels, so another question.
Originally Posted by
County
If I did convert back to stock, would the Simplex derailleur, which was intended for a five speed, work with a seven speed freewheel?
Possibly, but I doubt it (someone who's tried may chime in here) there are several vintage RD's that CAN handle that limit though (Suntour Cyclone for example I THINK)
Originally Posted by
County
Can anyone recommend a rim? Sun CR18 a good choice?
Sun CR18's seem to be a very popular choice round these parts. I've personally never used them.