Some general observations from 30 years ago.
Some Regina freewheels wobble, the primary body races were not machined parallel and or concentric to the freewheel to hub threads, back when they were available and cheap we would transfer the cogs to a better example.
Sometimes it was the hub that was the problem by the way.
The Campagnolo spacers were cool, even if one exclusively used Campagnolo hubs there was minor variation, the .5 or 1mm size would get one to the magic space of not having to adjust the rear derailleur no matter what whee l one used. Better yet was to check the spacing prior to building a wheel... But that¹s mechanic's logic.
A steel Sturmey spacer was useful if needed as it had enough width to avoid the crushed alloy spacer problem, but they only came in one width.
If one is having big-big spoke plucking, listen to the bike, avoid that gear. Under most circumstances if one looks on a gear chart there is a duplicate (or very close) ratio elsewhere. I always set bikes up chain safe , so that gear could be used, but it is the ratio that stresses things the greatest. Save the chain & components, stay away.
Regina cogs do sometimes "cup", I hate when that happens, I saw it most often when one was trying to change cogs, brute force vs. the frail.
John Jorgensen
Palos Verdes Ca