On a stock 1980 FLH
To Coil
Battery through circuit breaker, to Igniton Key switch, to ignition relay, to kill switch, to plus side of coil.
Basics Needed;
With no kill switch, no circuit breaker, no fuse, ect. You could run directly from the battery through on/off switch to + side of coil.
Not responsible for fires, burnt harness, etc.
Both plus and minus side of the coil go to the stock Electronic Module. Guessing aftermarket would be similiar.
Push Button starter. Your talking on the handle bars right? You did say the starter was wire directly to the battery, but I am guessing there is a starter soliniod in the picture somewhere. If not you will need one.
12 volt HEAVY wire from the + side of the battery to starter soliniod. Another HEAVY wire from other large terminal on starter soliniod to starter.
(Not responsible for fire, wrong gauge of wire here will make one )
Then if your bypassing relays and everthing else. You will need a momentary switch that send 12 volts to the small terminal on the starter soliniod. (This will activate the soliniod and connect the two large wires(Battery to Starter).
You could pick this 12 volts up from the same switch used for the coil. But you still need the momentary switch to turn the starter.
I would consider fuse or circuit breakers.