The vendor selling the engine should always be the best source for information and should be able to supply a wiring schematic. You're dealing with a good outfit and I'm sure they'll help you get the wiring sorted.
There's really not all that much involved, although I'd not try convincing anyone of this fact on the first exposure. Broken down, it's really just the CDI + switched ground, for the kill switch function and the charging circuit. There's a neutral light lead, coming from the switch located above the countershaft, easy to identify. If your bike is a K0, the speedo won't have a neutral light, you don't have to use the lead.
You'll have to change the coil to a CDI-compatible version...that should have come with the engine.
The charging & lighting are usually yellow & white leads. The reg/rec unit supplied with the engine is wired a little differently than the old selenium diode. The white lead is the diode (rectifier) input. Yellow goes to the regulator input and is "T'd" with the headlight switch power feed. That leaves one (+) output lead that goes to the battery and a (-). Once you identify which pin/spade corresponds with which lead, this is easy stuff.
The CDI module should plug into the adapter pigtail...leaving a switched ground that goes to the keyswitch, the primary coil output, which plugs into the secondary HT coil lead...and possibly a system ground lead.
Beyond this, it's just going to 12v bulbs, 12v battery and if you're running turn signals a 12v flasher relay. That's all there is to one of these electrical systems.
Now, if your eyes glazed over and you're thinking "wtf is he rambling on about? this makes no sense to me", no worries. There are other ways to sort the new wiring. And, there's always the option of learning this stuff for yourself, one, single lead at a time...if you are so motivated...for future use.
