I'm not familiar with that bike at all. But I think you're on the right track. You need a rectifier to convert AC to DC, to run LED s. I don't know if you need the regulator or not. On our CT70s, the (half wave) rectifier cuts the available power almost in half. But LEDs don't need as much power to work well.
In my personal experience...major electrical changes are never...just THAT simple.
Yes, the selenium half wave rectifier is on a separate circuit from the magneto to charge the 6v battery which then apparently acts like a voltage regulator for the DC side of things used for the turn signals, horn and brake light. I suppose an alternative is to use the battery supplied feed to the horn to power the headlight and taillight which as LEDs would have much lower current draw.
Well the, seemingly best, trick for our CTs, is to convert to a single, FULL wave, DC setup.
Our bikes stator/magneto's are split into 2 different circuits...sounds like yours is the same... So you get rid of the center tap from the lighting coil, then use the entire lighting coil to power 1 DC battery circuit, to power everything.
But that's usually done for 12v systems. I'm not sure if you can do it with 6v systems or not.
On our 6v CT70’s the lighting coil needs to have the ground lifted there are threads on this site on how to do that. There are a few mods to the harness that are also required. The idea is convert to 12vdc using a full wave regulator and rewound light coil then using the battery to power the lights and the regulator to charge the battery and when the motor is running to power the lights and charge the battery. I’ve done that and it works very well even night riding for hours is okay