please ignore the suggestion to use water on machines like this... Sewing Machine Oil only on the painted(or once painted) and your metal cleaner of choice on the metal. Water is BAD when the paint is no longer 100% and the water can seep under.
It is certainly using the Howe patents but it is not a Howe (neither AB or Elias)
Right off the top, I would guess Heid and Nau or the like. I would need to see the underside to make a better guess.
The key unique identifiers are:
two spool pins and their locations
the top tension and location
the needle screw
the base casting
Shuttle/bobbin
needle plate size/shape
100% correct that it is a bad buy without the shuttle and bobbin. In example, I have three machines that have no shuttle because the shuttle is harder to locate than the machine. I asked my expert buddy on one recently and his reply was to find a shuttle I would be better off finding a rusted out machine with one.
If you do decide not pursue this, let me know, I might.