My Standard Modern lathe originally came with a 3 phase 240 volt, 3 HP motor. As I do not have 3 phase power in my garage I bought a 3HP single phase reversible motor. My original drum switch was missing along with the original 3 phase motor. I bought a Square D drum switch off eBay.
This is how I wired my motor to my drum switch to allow me to reverse it.
These are the basic wiring diagrams of the motor and drum switch.
Motor and drum switch basic diagrams
These are the wiring connections I used. The only issue I have with doing it this way is that L2 is always connected to wire 4 on the motor. Because I have a motor contactor and overload between the L2 to wire 4 connection things should be fine.
Single phase motor to drum switch