Nearly impossible to help without seeing the type of winding.
You effectively have two 3 phase windings, each is 2 pole. Each winding on its own should run correctly but the current rating will only be half so you cant run it at full load continuously but you should be able to run it light on each winding connected in delta. If you can get that far then you are well on the way to being able to series connect the 2 windings and then your starting current should drop well down over that of a single winding.
The awkward bit is to do the parallel connections such that the windings are still in phase.
If you look up typical 2 pole winding diagrams you should easily be able to see if the thing is consequent pole or a 2 layer winding. Somehow you need to identify the 2 individual coils for each phase per pole. They may be wound in the same slots, adjacent slots or with a consequent pole you may have 2 machines wound in there as mirror images.
I would have thought it would be easy to distinguish the phases because of the coil displacement, having sorted the phases then you should be able to see how the duplicate coils are fitted in.
I think that if you can get it running as a parallel delta with a pair of leads for each phase then it would start equally well in star and that would be simpler to puzzle out.
Flux