Old freewheel replacement

[Captain Argo]

Looking at the info you provided (very helpful, thank you), it appears that I probably have either a Sun Tour "Ultra" 7 speed, or a Sun Tour "Microdrive". While the Microdrive appears to be fairly unique in its specs, the Ultra 7 seems like it has nearly identical cog spacing to the Shimano HG, and differs only in overall width. If I do indeed have the Ultra 7, can I assume that a Shimano HG freewheel would be compatible with the old shifters?