you are facing what is called hot soak problem - in this case your ignition switch contacts are worn to the point that the required amps to pull in the solenoid of the starter are not being bridged.
To test the starter itself when hot, apply 12V direct to the solenoid plunger, if the starter spins - its good and the problem is in the wiring or the ignition switch. To verify the switch - you need a 12V sealed headlamp from a bolan, ravi etc, and connect both high and low together, and earth it appropriately, connect the starter small wire to the lamp, It should glow bright - if its dim you dont have the required amps coming through.
To remedy this you need to either replace the switch or install a HD relay in the starter circuit.
The reason I said to use a headlamp and not a test lamp is because the headlamp with both filaments connected is that it will apply a load of 10 amps to the circuit, About nearly the same what is required to pull in the starter solenoid.
btw - the bushings you replaced are originally zeolite - which is porous material and is lubed for life, if you used anything else then it will be short lived, you should also have applied a dab of FRESH CV joint grease to the ends. Also a very very light coating of CV joint grease on the entire ring gear on the flywheel and starter gear.