Chris, not an answer to your question about the quality of these clone distributors, but regarding the distributor cap being loose ("moves too freely").
That is typical with this style Bosch distributor (assuming you have the Bosch and not the MM). The same basic Bosch design of distributor has been used on millions of vehicles for many decades all around the world, and they all have caps that can rotate a couple degrees. Combined with those silly spring-steel clips to hold it on, and they really aren't very accurate in today's terms. But that was sufficient back with Bosch designed them. Usually the cap will not move once you get everything set and don't touch it, so it really isn't a huge problem.
However there are a couple other factors to consider with this.
1) There should be a plastic 'dust shield' between the cap and the dizzy body. And the little 'notch' in it (that mates with the notch in the body) should be in good shape. With this cover in good condition and in place there is much less play with the cap. Unfortunately this cover is usually chewed up or completely missing, allowing more "free movement" of the cap. I haven't looked to see if these dust covers can be purchased new but considering how common this Bosch dizzy is I suspect they can.
2) The caps are pretty universal fitting. Most of the ones designed for this general model of Bosch dizzy can be used on any of them. There are a few odd exceptions but the differences are very minor. So there is a 99+% chance the late cap will work on the clone dizzy you are referring to.
3) Be careful with those steel cap-retainer clips when the cap is off. They will flop inward toward the working mechanism inside the dizzy and if the engine is turned (dizzy is rotated) the clips can damage the reluctor wheel (on electronic versions). This is very easy to happen when performing a tune-up and will pretty much ruin the dizzy.