I have the intake youre looking for.
just picked it up for storage, was a little dirty so its currently soaking in de greaser.
I was going to start looking for a place to restore it , but would also sell it as is.
Mine is a small lettered cobra intake (lettering at a slight angle) has firing order on back, but I dont recall seeing a S1MS... part number , will look again tomorrow
If im not mistaken, the small lettered intakes without a Ford engineering (part) number came on some of the early GT350's and 289 street cobra.
I will email you once i get pics