...I don't know his freewheel specifically, but generally the older Suntour and Shimano freewheels I've chosen to work with have the two smallest cogs threaded, and they hold the larger cogs in place on the lower part of the freewheel body. They usually have the spacer integral to the cog, so flipping them is not an option. And it is usually on the small sprockets that wear shows up the fastest, at least on the freewheels I work on. The larger cogs can be flipped on these older freewheels, because they are only positioned by tabs. But even then it's not an ideal solution, because the teeth are usually taper cut in one direction, to assist shifting. So you end up with the taper on the teeth going the wrong way. Still works, but not as well.

By far the best situation is to have a stock of old freewheels that are made by the same company, roughly contemporaneous, that you can disassemble and rob for parts. (Same model if possible.) Even the newer freewheels made by the same company are often incompatible as the design evolves over the years. Suntour cogs come in a bewildering array of inner diameters and methods of attachment over the years.