Have a wiring diag:
How to wire it isn't the question. Which wires are H1, H2, X1, X2, etc. is the question.
Series light bulb or Variac (will use 120 mains for testing as that is the only Variac I have...) seems the answer.
Remaining question: are H1/2 and H3/4 primary windings interchangeable? X1/2 and X3/4 windings interchangeable?