A Singer 201 sounds a lot like your description. Class 66 horizontal bobbin, the same style of top tension as a 66 and a stitch length regulator like a model 15. Singer 1200s were similar but with a knee lift. I'm kind of kicking myself for not buying a 1200 I saw last summer for $50. I probably could have came up with the money if I really wanted to and I'll be lucky if I ever see one again for that price. I'm not sure when Singer stopped production of the 201s. The potted motor 201s tend to turn up more often than those designed for treadle, handcrank or external motor applications.
Rodney