As with everything Chinese, there's a lot of exceptions to the rules with the Kalashnikovs (and the same applies to many countries that made the rifle). You'll notice a lot of "most," "some," and "almost all" words when describing the Type 56 as the rules sometimes went out the window.
However, practically all the military Chinese Type 56 rifles have no threaded muzzle (with the exception of the very early ones) The threaded muzzle is found on some export versions (some military and most commercially sold semi-autos).
The older milled receiver variants with the spike bayonet have threaded muzzles. The later stamped receiver variants with the spike bayonet almost never had a threaded muzzles. However, almost all the later imported commercial semi-autos with the spike bayonet have threaded muzzles.
I have hundreds of photos of various Chinese rifles and wish I could throw them all on here but just too many. However, here's some that can serve as food for thought regarding your project:
Type 56 with full buttstock/milled receiver/spike bayonet - threaded muzzle:
Type 56 with full buttstock/milled receiver (commonly called the "M22" for export purposes) - threaded muzzle:
Type 56 with underfolding buttstock/milled receiver - no threaded muzzle:
Type 56 with full buttstock/stamped receiver/spike bayonet - no threaded muzzle:
Type 56 with full buttstock/stamped receiver/spike bayonet (export version/markings) - threaded muzzle:
Type 56 with underfolding buttstock/stamped receiver - no threaded muzzle:
Type 56 with side-folding buttstock/stamped receiver (with export version/markings) - threaded muzzle:
Type 56 with side-folding buttstock/stamped receiver (with export version/markings) - no threaded muzzle:
Type 56 with side-folding buttstock/stamped receiver - no threaded muzzle: