Based on your question, can we assume you are looking to attach a temporary jumper from the battery to the ballast resistor in order to test fire your engine? If so, refer to figure 1 below, and the jumper takes the place of the "wire to ignition switch".
Note that figure 1 has the power coming from the ignition switch, which is the customary wiring connection.
If you do run a jumper from the battery to the the ballast resistor in lieu of the connection from the ignition switch, make sure you tag and disconnect the connection from the ignition switch (don't want to back feed the ignition circuit, because I don't know what harm that may or may not cause) and remember to disconnect the jumper wire when you're not trying to run the engine.
The PO swapped out the body tub, so the only connections are on the engine itself. The ballast is currently going to the engine block, which makes no sense and was racking my brain. Thank you for the help!